• Typical Serial Port Baud Rates
• Common Serial Port Baud Rates Today

Professional A/V equipment employed in signal management systems is commonly controlled by the RS-232 serial communication protocol. Amplifiers, switchers, dimmers, extenders, projectors and matrix switchers are just a few examples of the kinds of equipment controlled by the RS-232 protocol.

With the exception of its local console port, all of your Opengear device's RS-232 and USB serial ports are set to Disabled Mode by default. To allow network connections to console ports, you must configure at least these settings at a minimum: Set the Common Settings to match the connected device (not generally required for USB); Set the port to Console Server Mode (aka portmanager mode). Common serial port speeds Bit rate (Baud rate) Time per bit Windows predefined serial port speed Other reasons that this speed is common 50 bit/s: 20000 μs: No: Listed in PC16550D datasheet: 75 bit/s: 13333.3 μs: Yes: 110 bit/s: 9090.9 μs: Yes: Bell 101 modem: 134.5 bit/s: 7434.9 μs: Yes: 150 bit/s: 6666.6 μs: Yes: 300 bit/s: 3333.3 μs: Yes: Bell 103 modem or V.21: 600 bit/s. Aug 06, 2019  As the baud rate increases the serial cable connecting your A/V equipment and its controlling system must decrease. Generally a 100 foot cable is appropriate for 1200 to 2400 baud. For 9600 baud your cable should be a maximum length of 50 feet and you need to shorten this to 20 feet is you are transmitting at 19200 baud. The baud rate you select in the software must match the baud rate of the datalogger serial port. For example, CR200-series dataloggers and CR10X dataloggers are always 9600 baud. CR1000 and similar dataloggers can handle baud rates up to 115200. The CR1000 defaults to a baud rate of -115200, which means 115200 with autobaud enabled. Baud rates can be just about any value within reason. The only requirement is that both devices operate at the same rate. One of the more common baud rates, especially for simple stuff where speed isn't critical, is 9600 bps. Other 'standard' baud are 1200, 2400, 4800, 19200, 38400, 57600, and 115200.

Advanced installer download. Download Advanced Installer. Free Download. This is a unified package containing the complete Advanced Installer application, which includes Freeware. Our software library provides a free download of Advanced Installer 16.3. The most popular versions of the tool 11.6, 11.5 and 11.4. Some of the program aliases include 'advanced installer7.21'. Commonly, this program's installer has the following filenames: advinst.exe, AdvancedInstaller.exe, Repackager.exe and updater.exe etc. Advanced Installer 15.7 Key Download. Advanced Installer Keygen is a user-friendly and powerful Windows Installer application which is authoring enabling designers to produce reliable MSI packages which satisfy in place in the current Microsoft Windows logo certification tips. Very simple to build utilization of, useful, faster and lightweight. Download Advanced Installer for Windows PC from FileHorse. 100% Safe and Secure Free Download (32-bit/64-bit) Latest Version 2019.

An understanding of the underlying technology of the RS-232 protocol can be indispensable when faced with problems while using your equipment. Knowing what to look for can minimize the time spent troubleshooting RS-232 connections.

In this article we will attempt to give you a basic understanding of RS-232 connections and help you resolve any serial port problems you encounter.

Contents

1. Serial port troubleshooting
   

RS-232 Protocol

The Electronic Industries Association (EIA) originally defined RS-232 in 1962 as a recommended standard (RS) for interfacing with a modem. In January 1987 the standard was amended to the most current version, RS-232D. These amendments were made to ensure compatibility with international standards CCITT V.24, V.28, and IS2110.

RS-232 Pinouts

Below are the standard pin-outs for the RS-232 protocol for IBM compatible computers. The most common connections contain either a 9-pin or a 25-pin connector.

Not all pins in the 25-pin connector are used for transmitting data. The extra pins are commonly used for port loop-back testing. The 9-pin and the 25-pin connectors have opposite designations for their number 2 and 3 pins. A/V equipment usually uses a 9-pin connector for its RS-232 connections. In many cases the pin-outs can be different on your A/V equipment and the controlling system or computer. An example would be where the 2 and 3 pins are reversed which allows the connection to be made with pin-to-pin wiring between a 9-pin connector and 9-pin cable. “Terminal block” connectors are becoming popular with A/V equipment manufacturers. These connectors enable easy installation with no soldering required.

Voltage Ranges

RS-232 pins have a standard voltage range of -15V to +15V for all of its signal pins. Voltage swings that occur while transmitting data can total 30V. RS-232 ports can work with voltages as low as -5V to +5V. Compatibility with different equipment types is made possible by the wide range of voltages that the RS-232 can use and this also helps to minimize interference by allowing for a greater noise margin.

RS-232 signal lines can generate substantial electrical noise due to the large voltage fluctuations. This means you should not run this signal close to high-impedance microphone or audio lines. If you do require these signals to be running near each other you need to properly shield all of your audio wires.

Baud Rate

Baud rate measures the speed of data transmission between two ports and is generally thought of as bits per second. The RS-232 protocol controls the baud rate. Baud rates usually fall into the range of 1200 to 19200. Starting at 1200, rates double through the common baud rates of 1200, 2400, 4800, 9600 and 19200.

Cable Length Limitations

As the baud rate increases the serial cable connecting your A/V equipment and its controlling system must decrease. Generally a 100 foot cable is appropriate for 1200 to 2400 baud. For 9600 baud your cable should be a maximum length of 50 feet and you need to shorten this to 20 feet is you are transmitting at 19200 baud.

Troubleshooting

Serial port troubleshooting falls into two broad categories. Software incompatibilities or conflicts can cause your connection problems as can physical connection problems with your hardware.

Hardware

One of the most common serial port errors that installers encounter when connecting a device to the control system is incorrect wiring. Most control systems only require the connection of two wires to the controlled device. The Transmit (XMT) and Ground (GND) pins on the control system are connected to the Receive (RCV) and Ground (GND) pins on the controlled device respectively, as shown below (Fig. 1)

If the control system needs to receive a response from the controlled device, a third wire will also need to be connected (Fig. 2). For example, this is the recommended wiring if you are controlling a device through your computer’s COM port.

Confirming a Proper Connection

If all of the pins are not labelled it can be difficult to tell if the wiring between control system port and controlled device port has been done correctly. If a terminal block connector is in use you can use a voltmeter to monitor the voltage and ascertain that the connection is good. Test the voltage with the voltmeter set to “DC”. You want the reading between the RCV pin and the GND pin on the terminal block connector to be between -12V and -6V. Your XMT line should have the same reading as seen below (Fig. 3)

If the voltage on the receive line remains at 0 volts after you have connected the control system and the controlled device, this indicates that your serial port connection problems are the result of the Transmit and Receive lines being reversed (Fig. 4).

Software

If your com port error persists after you have verified the hardware connection the problem may lie in the software communications settings for both the controlling system and the controlled device.

The software settings must be identical for correct communication between the devices. Baud rate is one parameter that must match on both systems, so if your control system is operating at 2400 baud, you need to have your device set to 2400 baud as well. Data Bits, Parity and Stop Bits are other parameters that must be set identically for communication to flow. The number of bits transmitted in a single character is referred to as the Data Bits and can be set to either 7 or 8. Parity defines if the number of 1s in a single transmission is odd or even. It can be set to None if parity is not important to your application.

The Stop Bit can be set to 0, 1 or 2 and defines the end of the transmission. A/V devices are usually set with Data Bits at 8, Parity at None and 1 Stop Bit. This is known as an “8 n 1” setting. If you are troubleshooting serial port communication issues, check that all these settings are the same on both ends of your connection.

Serial Port Monitor is a software tool offered by Eltima Software that works as an aid in serial port communication troubleshooting. It can greatly reduce the time required to find and resolve issues with your serial port communications.

Serial Port Monitor assists in com port troubleshooting by enabling you to monitor, log and analyze any of your serial ports. The software tool’s user interface lets you look at this data in a number of different views that will help you track down problems quickly. You can also emulate sending data to a serial device and playback sessions so you can review multiple instances of the same data being sent to a port. This allows you to search for differences that may lead you to the solution of your problem.

Serial Port Monitor can prove to be an indispensable tool when confronted with serial port communication problems. Put it in your software toolbox today and start streamlining your troubleshooting sessions.

Serial Port Monitor

In computing, a serial port is a serial communication interface through which information transfers in or out one bit at a time (in contrast to a parallel port).^[1] Throughout most of the history of personal computers, data was transferred through serial ports to devices such as modems, terminals, and various peripherals.

While such interfaces as Ethernet, FireWire, and USB all send data as a serial stream, the term serial port usually identifies hardware compliant to the RS-232 standard or similar and intended to interface with a modem or with a similar communication device.

Modern computers without serial ports may require USB-to-serial converters to allow compatibility with RS-232 serial devices. Serial ports are still used in applications such as industrial automation systems, scientific instruments, point of sale systems and some industrial and consumer products. Server computers may use a serial port as a control console for diagnostics. Network equipment (such as routers and switches) often use serial console for configuration. Serial ports are still used in these areas as they are simple, cheap and their console functions are highly standardized and widespread. A serial port requires very little supporting software from the host system.

• 1Hardware
• 3Settings

Hardware[edit]

Some computers, such as the IBM PC, use an integrated circuit called a UART. This IC converts characters to and from asynchronous serial form, implementing the timing and framing of data in hardware. Very low-cost systems, such as some early home computers, would instead use the CPU to send the data through an output pin, using the bit banging technique. Before large-scale integration (LSI) UART integrated circuits were common, a minicomputer would have a serial port made of multiple small-scale integrated circuits to implement shift registers, logic gates, counters, and all the other logic for a serial port.

Early home computers often had proprietary serial ports with pinouts and voltage levels incompatible with RS-232. Inter-operation with RS-232 devices may be impossible as the serial port cannot withstand the voltage levels produced and may have other differences that 'lock in' the user to products of a particular manufacturer.

Low-cost processors now allow higher-speed, but more complex, serial communication standards such as USB and FireWire to replace RS-232. These make it possible to connect devices that would not have operated feasibly over slower serial connections, such as mass storage, sound, and video devices.

Many personal computer motherboards still have at least one serial port, even if accessible only through a pin header. Small-form-factor systems and laptops may omit RS-232 connector ports to conserve space, but the electronics are still there. RS-232 has been standard for so long that the circuits needed to control a serial port became very cheap and often exist on a single chip, sometimes also with circuitry for a parallel port.

DTE and DCE[edit]

The individual signals on a serial port are unidirectional and when connecting two devices the outputs of one device must be connected to the inputs of the other. Devices are divided into two categories data terminal equipment (DTE) and data circuit-terminating equipment (DCE). A line that is an output on a DTE device is an input on a DCE device and vice versa so a DCE device can be connected to a DTE device with a straight wired cable. Conventionally, computers and terminals are DTE while modems and peripherals are DCE.

If it is necessary to connect two DTE devices (or two DCE devices but that is more unusual) a cross-over null modem, in the form of either an adapter or a cable, must be used.

Male and female[edit]

Generally, serial port connectors are gendered, only allowing connectors to mate with a connector of the opposite gender. With D-subminiature connectors, the male connectors have protruding pins, and female connectors have corresponding round sockets.^[2] Either type of connector can be mounted on equipment or a panel; or terminate a cable.

Connectors mounted on DTE are likely to be male, and those mounted on DCE are likely to be female (with the cable connectors being the opposite). However, this is far from universal; for instance, most serial printers have a female DB25 connector, but they are DTEs.^[3]

Connectors[edit]

While the RS-232 standard originally specified a 25-pin D-type connector, many designers of personal computers chose to implement only a subset of the full standard: they traded off compatibility with the standard against the use of less costly and more compact connectors (in particular the DE-9 version used by the original IBM PC-AT). The desire to supply serial interface cards with two ports required that IBM reduce the size of the connector to fit onto a single card back panel. A DE-9 connector also fits onto a card with a second DB-25 connector. Starting around the time of the introduction of the IBM PC-AT, serial ports were commonly built with a 9-pin connector to save cost and space. However, presence of a 9-pin D-subminiature connector is not sufficient to indicate the connection is in fact a serial port, since this connector is also used for video, joysticks, and other purposes.

Some miniaturized electronics, particularly graphing calculators and hand-held amateur and two-way radio equipment, have serial ports using a phone connector, usually the smaller 2.5 or 3.5 mm connectors and use the most basic 3-wire interface.

Many models of Macintosh favor the related RS-422 standard, mostly using German mini-DIN connectors, except in the earliest models. The Macintosh included a standard set of two ports for connection to a printer and a modem, but some PowerBook laptops had only one combined port to save space.

Since most devices do not use all of the 20 signals that are defined by the standard, smaller connectors are often used. For example, the 9-pin DE-9 connector is used by most IBM-compatible PCs since the IBM PC AT, and has been standardized as TIA-574. More recently, modular connectors have been used. Most common are 8P8C connectors, for which the EIA/TIA-561 standard defines a pinout, while the 'Yost Serial Device Wiring Standard'^[4] invented by Dave Yost (and popularized by the Unix System Administration Handbook) is common on Unix computers and newer devices from Cisco Systems. 10P10C connectors can be found on some devices as well. Digital Equipment Corporation defined their own DECconnect connection system which is based on the Modified Modular Jack (MMJ) connector. This is a 6-pin modular jack where the key is offset from the center position. As with the Yost standard, DECconnect uses a symmetrical pin layout which enables the direct connection between two DTEs. Another common connector is the DH10 header connector common on motherboards and add-in cards which is usually converted via a cable to the more standard 9-pin DE-9 connector (and frequently mounted on a free slot plate or other part of the housing).

Pinouts[edit]

The following table lists commonly used RS-232 signals and pin assignments.^[5]

The signal ground is a common return for the other connections; it appears on two pins in the Yost standard but is the same signal. The DB-25 connector includes a second 'protective ground' on pin 1, which is intended to be connected by each device to its own frame ground or similar. Connecting this to pin 7 (signal reference ground) is a common practice but not recommended.

Note that EIA/TIA 561 combines DSR and RI,^[10][11] and the Yost standard combines DSR and DCD.

Powered serial port[edit]

Some serial ports on motherboards or add-in cards provide jumpers that select whether pin 1 of the DE-9 connector connects to DCD or a power supply voltage, and whether pin 9 of the DE-9 connector connects to RI or a power supply voltage. The power supply voltage can be +5V, +12V, +9V, or ground. (Selection varies by vendor.) The power is intended for use by point-of-sale equipment. Makers include Dell^[12], HP, and others^[13] (This is not an official standard.)

Hardware abstraction[edit]

Operating systems usually create symbolic names for the serial ports of a computer, rather than requiring programs to refer to them by hardware address.

Unix-like operating systems usually label the serial port devices /dev/tty*. TTY is a common trademark-free abbreviation for teletype, a device commonly attached to early computers' serial ports, and * represents a string identifying the specific port; the syntax of that string depends on the operating system and the device. On Linux, 8250/16550 UART hardware serial ports are named /dev/ttyS*, USB adapters appear as /dev/ttyUSB* and various types of virtual serial ports do not necessarily have names starting with tty.

The DOS and Windows environments refer to serial ports as COM ports: COM1, COM2,.etc. Ports numbered greater than COM9 should be referred to using the .COM10 syntax.^[14]

Common applications for serial ports[edit]

The RS-232 standard is used by many specialized and custom-built devices. This list includes some of the more common devices that are connected to the serial port on a PC. Some of these such as modems and serial mice are falling into disuse while others are readily available.

Serial ports are very common on most types of microcontroller, where they can be used to communicate with a PC or other serial devices.

• Dial-up modems
• Configuration and management of networking equipment such as routers, switches, firewalls, load balancers
• GPS receivers (typically NMEA 0183 at 4,800 bit/s)
• Bar code scanners and other point of sale devices
• LED and LCD text displays
• Satellite phones, low-speed satellite modems and other satellite based transceiver devices
• Flat-screen (LCD and Plasma) monitors to control screen functions by external computer, other AV components or remotes
• Test and measuring equipment such as digital multimeters and weighing systems
• Updating firmware on various consumer devices.
• Hobbyist programming and debugging MCU's
• Stenography or Stenotype machines
• Software debuggers that run on a second computer
• Industrial field buses
• Computer terminal, teletype
• Older digital cameras
• Networking (Macintosh AppleTalk using RS-422 at 230.4 kbit/s)
• Older GSMmobile phones
• IDEhard drive^[15][16]repair^[17][18]

Since the control signals for a serial port can be easily turned on and off by a switch, some applications used the control lines of a serial port to monitor external devices, without exchanging serial data. A common commercial application of this principle was for some models of uninterruptible power supply which used the control lines to signal loss of power, low battery, and other status information. At least some Morse code training software used a code key connected to the serial port, to simulate actual code use. The status bits of the serial port could be sampled very rapidly and at predictable times, making it possible for the software to decipher Morse code.

Settings[edit]

Many settings are required for serial connections used for asynchronous start-stop communication, to select speed, number of data bits per character, parity, and number of stop bits per character. In modern serial ports using a UART integrated circuit, all settings are usually software-controlled; hardware from the 1980s and earlier may require setting switches or jumpers on a circuit board. One of the simplifications made in such serial bus standards as Ethernet, FireWire, and USB is that many of those parameters have fixed values so that users cannot and need not change the configuration; the speed is either fixed or automatically negotiated. Often if the settings are entered incorrectly the connection will not be dropped; however, any data sent will be received on the other end as nonsense.

Speed[edit]

Serial ports use two-level (binary) signaling, so the data rate in bits per second is equal to the symbol rate in baud. A standard series of rates is based on multiples of the rates for electromechanical teleprinters; some serial ports allow many arbitrary rates to be selected. The port speed and device speed must match. The capability to set a bit rate does not imply that a working connection will result. Not all bit rates are possible with all serial ports. Some special-purpose protocols such as MIDI for musical instrument control, use serial data rates other than the teleprinter series. Some serial port systems can automatically detect the bit rate.

The speed includes bits for framing (stop bits, parity, etc.) and so the effective data rate is lower than the bit transmission rate. For example, with 8-N-1 character framing only 80% of the bits are available for data (for every eight bits of data, two more framing bits are sent).

Bit rates commonly supported include 75, 110, 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200 bit/s.^[20]

Crystal oscillators with a frequency of 1.843200 MHz are sold specifically for this purpose. This is 16 times the fastest bit rate and the serial port circuit can easily divide this down to lower frequencies as required.

Data bits[edit]

The number of data bits in each character can be 5 (for Baudot code), 6 (rarely used), 7 (for true ASCII), 8 (for most kinds of data, as this size matches the size of a byte), or 9 (rarely used). 8 data bits are almost universally used in newer applications. 5 or 7 bits generally only make sense with older equipment such as teleprinters.

Most serial communications designs send the data bits within each byte LSB (least significant bit) first. This standard is also referred to as 'little endian.' Also possible, but rarely used, is 'big endian' or MSB (most significant bit) first serial communications; this was used, for example, by the IBM 2741 printing terminal. (See Bit numbering for more about bit ordering.) The order of bits is not usually configurable within the serial port interface. To communicate with systems that require a different bit ordering than the local default, local software can re-order the bits within each byte just before sending and just after receiving.

Parity[edit]

Parity is a method of detecting errors in transmission. When parity is used with a serial port, an extra data bit is sent with each data character, arranged so that the number of 1 bits in each character, including the parity bit, is always odd or always even. If a byte is received with the wrong number of 1s, then it must have been corrupted. However, an even number of errors can pass the parity check.

Electromechanical teleprinters were arranged to print a special character when received data contained a parity error, to allow detection of messages damaged by line noise. A single parity bit does not allow implementation of error correction on each character, and communication protocols working over serial data links will have higher-level mechanisms to ensure data validity and request retransmission of data that has been incorrectly received.

The parity bit in each character can be set to one of the following:

• None (N) means that no parity bit is sent at all.
• Odd (O) means that parity bit is set so that the number of 'logical ones' must be odd.
• Even (E) means that parity bit is set so that the number of 'logical ones' must be even.
• Mark (M) parity means that the parity bit is always set to the mark signal condition (logical 1).
• Space (S) parity always sends the parity bit in the space signal condition (logical 0).

Aside from uncommon applications that use the last bit (usually the 9th) for some form of addressing or special signaling, mark or space parity is uncommon, as it adds no error detection information. Odd parity is more useful than even, since it ensures that at least one state transition occurs in each character, which makes it more reliable. The most common parity setting, however, is 'none', with error detection handled by a communication protocol.

Stop bits[edit]

Stop bits sent at the end of every character allow the receiving signal hardware to detect the end of a character and to resynchronise with the character stream. Electronic devices usually use one stop bit. If slow electromechanical teleprinters are used, one-and-one half or two stop bits are required.

Conventional notation[edit]

The data/parity/stop (D/P/S) conventional notation specifies the framing of a serial connection. The most common usage on microcomputers is 8/N/1 (8N1). This specifies 8 data bits, no parity, 1 stop bit. In this notation, the parity bit is not included in the data bits. 7/E/1 (7E1) means that an even parity bit is added to the 7 data bits for a total of 8 bits between the start and stop bits. If a receiver of a 7/E/1 stream is expecting an 8/N/1 stream, half the possible bytes will be interpreted as having the high bit set.

Flow control[edit]

In many circumstances a transmitter might be able to send data faster than the receiver is able to process it. To cope with this, serial lines often incorporate a 'handshaking' method, usually distinguished between hardware and software handshaking.

Hardware handshaking is done with extra signals, often the RS-232 RTS/CTS or DTR/DSR signal circuits. Generally, the RTS and CTS are turned off and on from alternate ends to control data flow, for instance when a buffer is almost full. DTR and DSR are usually on all the time and, per the RS-232 standard and its successors, are used to signal from each end that the other equipment is actually present and powered-up. However, manufacturers have over the years built many devices that implemented non-standard variations on the standard, for example, printers that use DTR as flow control.

Software handshaking is done for example with ASCIIcontrol charactersXON/XOFF to control the flow of data. The XON and XOFF characters are sent by the receiver to the sender to control when the sender will send data, that is, these characters go in the opposite direction to the data being sent. The circuit starts in the 'sending allowed' state. When the receiver's buffers approach capacity, the receiver sends the XOFF character to tell the sender to stop sending data. Later, after the receiver has emptied its buffers, it sends an XON character to tell the sender to resume transmission. It is an example of in-band signaling, where control information is sent over the same channel as its data.

The advantage of hardware handshaking is that it can be extremely fast; it doesn't impose any particular meaning such as ASCII on the transferred data; and it is stateless. Its disadvantage is that it requires more hardware and cabling, and these must be compatible at both ends.

Typical Serial Port Baud Rates

The advantage of software handshaking is that it can be done with absent or incompatible hardware handshaking circuits and cabling. The disadvantage, common to all in-band control signaling, is that it introduces complexities in ensuring that a) control messages get through even when data messages are blocked, and b) data can never be mistaken for control signals. The former is normally dealt with by the operating system or device driver; the latter normally by ensuring that control codes are 'escaped' (such as in the Kermit protocol) or omitted by design (such as in ANSI terminal control).

If no handshaking is employed, an overrun receiver might simply fail to receive data from the transmitter. Approaches for preventing this include reducing the speed of the connection so that the receiver can always keep up; increasing the size of buffers so it can keep up averaged over a longer time; using delays after time-consuming operations (e.g. in termcap) or employing a mechanism to resend data which has been corrupted (e.g. TCP).

'Virtual' serial ports[edit]

A virtual serial port is an emulation of the standard serial port. This port is created by software which enable extra serial ports in an operating system without additional hardware installation (such as expansion cards, etc.). It is possible to create a large number of virtual serial ports in a PC. The only limitation is the amount of resources, such as operating memory and computing power, needed to emulate many serial ports at the same time.

Virtual serial ports emulate all hardware serial port functionality, including baud rate, data bits, parity bits, stop bits, etc. Additionally, they allow controlling the data flow, emulating all signal lines (DTR, DSR, CTS, RTS, DCD, and RI) and customizing pinout. Virtual serial ports are common with Bluetooth and are the standard way of receiving data from Bluetooth-equipped GPS modules.

Virtual serial port emulation can be useful in case there is a lack of available physical serial ports or they do not meet the current requirements. For instance, virtual serial ports can share data between several applications from one GPS device connected to a serial port. Another option is to communicate with any other serial devices via internet or LAN as if they are locally connected to computer (serial over LAN/serial-over-Ethernet technology). Two computers or applications can communicate through an emulated serial port link. Virtual serial port emulators are available for many operating systems including MacOS, Linux, NetBSD and other Unix-like operating systems, and various mobile and desktop versions of Microsoft Windows.

See also[edit]

• ITU-T/CCITT V.24 [de]
• ITU-T/CCITT V.28 [de]

References[edit]

1. ^Webopedia (2003-09-03). 'What is serial port? - A Word Definition From the Webopedia Computer Dictionary'. Webopedia.com. Retrieved 2009-08-07.
2. ^'Serial Cable Connection Guide'. CISCO. 2006-08-01. Retrieved 2016-01-31.
3. ^'RS232 - DTE and DCE connectors'. Lantronix. 2006-03-29. Retrieved 2016-01-31.
4. ^Yost Serial Device Wiring Standard
5. ^Ögren, Joakim. 'Serial (PC 9)'.
6. ^ ^abCyclom-Y Installation Manual, page 38, retrieved on 29 November 2008^{[permanent dead link]}
7. ^'RJ-45 8-Pin to Modem (ALTPIN option)'. Digiftp.digi.com. Retrieved 2014-02-08.
8. ^National Instruments Serial Quick Reference Guide, February 2007
9. ^'RJ-45 10-Pin Plug to DB-25 Modem Cable'. Digiftp.digi.com. Retrieved 2014-02-08.
10. ^Hardware Book RS-232D
11. ^RS-232D EIA/TIA-561 RJ45 Pinout
12. ^'OptiPlex XE Powered Serial Port Configuration'(PDF).
13. ^'Powered Serial Cards - Brainboxes'.
14. ^'HOWTO: Specify Serial Ports Larger than COM9'. Microsoft support. Retrieved 2013-10-26.
15. ^'Paul's 8051 Code Library, IDE Hard Drive Interface'. Pjrc.com. 2005-02-24. Retrieved 2014-02-08.
16. ^'IDE Hard Disk experiments'. Hem.passagen.se. 2004-02-15. Archived from the original on 2004-04-15. Retrieved 2014-02-08.
17. ^'The Solution for Seagate 7200.11 HDDs - Hard Drive and Removable Media issues - MSFN Forum'. Msfn.org. Retrieved 2014-02-08.
18. ^'Fixing a Seagate 7200.11 Hard Drive'. Sites.google.com. Retrieved 2014-02-08.
19. ^'SERIAL_COMMPROP structure'. Microsoft. 2018-04-22. Retrieved 2019-09-28.
20. ^ ^ab'DCB Structure'. Windows Dev Center. Microsoft. 2018-12-04. Retrieved 2019-09-28.
21. ^'PC16550D Universal Asynchronous Receiver/Transmitter With FIFOs'(PDF). Texas Instruments. May 2015. Retrieved September 25, 2019.
22. ^'BACnet MS/TP Overview Manual'(PDF). Neptronic. Retrieved September 26, 2019.
23. ^'MultiModem ZBA'(PDF). Multi-Tech Systems, Inc. January 2019. Retrieved September 26, 2019.
24. ^'Courier 56K Business Modem: User Guide: Controlling Data Rates'. USRobotics. 2007. Retrieved September 26, 2019.

Further reading[edit]

• Serial Port Complete: COM Ports, USB Virtual COM Ports, and Ports for Embedded Systems; 2nd Edition; Jan Axelson; Lakeview Research; 380 pages; 2007; ISBN978-1-931-44806-2.

External links[edit]

Common Serial Port Baud Rates Today