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- COMD is a program which lets you share serial devices such as modems
- over a network. Eventually COMD may include features specify to
- devices like dialing HAYESMODEMSs and passwords. Methods for
- configuring such features have been listed, but are not implemented
- and will bring unpredictable results.
-
- Possible uses for COMD include :
- o remote connection to serial printers - unlike pc's running LPD, COMD
- allows the host to perform accounting and eliminates the need for
- a local hard disk on the pc
-
- o can be easily modified to function as a dial out modem pool
-
- o could be modified to works as a dial out fax modem pool
-
- o can be used to let a remote host control lab equipment or
- collect data from remote sources
-
- To use COMD you will need a valid WATTCP.CFG file. Documentation on
- the general WATTCP programs provides that information and you are
- referred there for more details. Once PING and FINGER work, you may
- proceed on to the next paragraph.
-
- For each serial device you must add several lines to your WATTCP.CFG
- file. You must specify the following:
-
- COM.PORT = 1 | 2 | 3 | 4
- You will receive an error message on bootup if one of the specified
- ports does not exist.
- COM.PARITY = EVEN | ODD | NONE | MARK | SPACE
- COM.BITS = 5 | 6 | 7 | 8
- COM.STOP = 1 | 2
- COM.TCPPORT = some port number, 23 is TELNET
- COM.MODE = RS232 | TEST | HAYESMODEM
- To test a new device, use the TEST mode which will let you
- interactively 'talk' with the serial device.
- The HAYESMODEM mode is not implemented yet.
- COM.HANDSHAKE = XON | MODEM
- COM.DELAY = xxx
- xxx is minimum delay between transmissions in 10ths of a second.
- It is used to collect a reasonable amount of data before sending it
- over the network. A value of 0 is very greedy, 2 is very reasonable
- for terminal servers or modems, 10 is fine for laser printers.
-
- For example, to configure COM1 and COM2 you may use:
- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
- com.port=1 # simple modem
- com.mode=RS232 # vs. TEST (or HAYESMODEM)
- com.tcpport=23 # TELNET port
- com.handshake=XON # vs. MODEM
- com.delay=2 # in 1/10s of second pick 0 - 2, 0 is costly
- com.baud=9600
- com.parity=none
- com.bits=8
- com.stop=1
-
- com.port=2 # RS232 based printer
- com.mode=RS232
- com.tcpport=800 # user defined port
- com.handshake=XON
- com.delay=2 # in 1/10s of second pick 0 - 2, 0 is costly
- com.baud=9600
- com.parity=none
- com.bits=7
- com.stop=1
- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
-
- Up to four devices may be used similtaneously, but you should have a
- machine fast enough to handle those serial interrupts.
-
- You can do load leveling, where two devices are assigned to the same
- tcp port. That way, if one is busy, the other will be used. All
- you have to do is specify the *same* com.tcpport number for both
- and the software manages the rest.
-
- The com.delay value is the amount of time (in 100 millisecond quantities)
- during which COMD accepts characters from the RS232 port before it
- transmits the over the network. This produces a slight delay, but
- it reduces packets dramatically. For highly interactive sessions,
- 1 to 2 is reasonable. For others, 5 to 10 gives a delay between
- a half second and a full second.
-
- If you add new features to COMD, please send them back to me so others
- can benefit from your time and expertise.
-
-
- **** IMPORTANT NOTES ****
-
- Many people have their Ethernet cards set to irq 3 (interrupt level 3).
- In fact, that's how the cards usually arrive from the factory.
- Unfortunately irq 3 is also used by COM2 and COM4, and gives rise to
- a conflict. I didn't write the com libraries, I don't even have source
- for them, so I can't fix it. You can solve the problem by moving the
- card to a different interrupt.
-
- If you intend to use COMD, you should remember that the com port libraries
- (Litecomm) are copyrighted by Information Technology Ltd. and should be
- registerred with that company. I have no affiliation with ITL, I just
- downloaded these files from simtel and found they suited the task very
- nicely.
-
-