Commchk.doc Version 1.2
Documentation for the Serial protocol analizer
Commchk is used to analyze information on a serial line by
intercepting the information and allowing you to view the
captured information in either a HEX format or in an ASCII format.
The information captured may also be saved in files stored on disk.
Commchk performs this function by routing any information read from
com1 to com2 and any information read from com2 to com1, while
capturing the information for display and or saving to a file.
Commchk will split the screen into 2 windows, an upper window
and a lower window. the upper window will display the information
captured from com1 and sent to com2. The lower window will
display the information captured from com2 and sent to com1.
This program was developed to allow analyzing information being
send from a host computer to a slave computer to determine the
source of errors that were getting into the system.
Alternatively, Commchk can be used to allow a computer that does
not have a modem to access the modem of a second computer.
Commchk command line options are summarized as follows.
-I 0/1/2 all commands up to the next "I" command
are for the identified port.
0 = both ports
1 = com1
2 = com2
-B baud baud rates from 300 baud to 57600
baud are supported.
-P parity Allowable paritys are
EVEN, ODD, NONE
-W word length 7 or 8 bits
-S stop bits 1 or 2 stop bits
-f file name the file name must not have a length of
greater than 7 characters, not including
the path name. It is used to create create
2 files, one for information read from com1,
and one for information read from com2 by
appending the communications port number
and .fil to the end of the file name.
IE: -f test
generates test1.fil - com1 info
test2.fil - com2 info
Example startup command:
COMMCHK -I 1 -B 1200 -P E -W 7 -S 2 -I 2 -B 4800 -P N -W 8
THIS SETS COM1 TO 1200 BAUD, 7 BIT, EVEN PARITY, 2 STOP BITS
AND COM2 TO 4800 BAUD, NO PARITY, 8 BIT.
Commchk keyboard commands are summarized as follows.
F1 key - Help
O key - Open the currently active capture files
C key - Close the currently active capture files
D key - Toggle video display on and off
F key - Flush out all current serial port buffers
of all characters.
A key - place the display in ASCII mode
H key - place the display in HEX mode
Q key - Quit
R key - Toggle the RTS line
T key - Toggle the DTR line
L key - Toggle the line display status line
Commchk Startup defaults are as follows
2400 Baud, 8 Data bits, 1 Stop bit, No parity
No capture file
11/5/90 - Fixed serial protocol data errors.
11/13/90 - Modified help routine to not interrupt serial data flow.
Added Flush buffer command.
Modified asynchronous character send routine
errors that caused loss of characters.
Added code to allow setting of the serial
ports to different parameters.
Removed SHAREWARE message.
11/27/90 - Modified code to use only 8088/8086 code.
Added a line at the bottom of the status windows
that displays statistics about the serial port
Added code to allow toggling the RTS and DTR lines
Modified the asyncronous lines to have all serial port
IO completely asyncronously driven to assist in
performance on slower computers.
Written using Turbo C++ by:
Timothy L. Garrison
3003 W. Marquette Woods Rd.
Stevensville Mi. 49127