Appendix A Communications Protocol; Protocol Summary - Ametek Dycor CG1100 Series User Manual

COMMUNICATIONS PROTOCOL

Protocol Summary

> AAFddddCC[CR]
A[CR]
AddddCC[CR]
NEE[CR]
Character
>
AA
F
dddd
cc
A
n
EE
[cR]
The protocol is an ASCII master/slave, command/response communication
protocol with the master initiating all transfers.
All elements of this protocol are sent as ASCII characters. The Start Flag
is the character '>', hex 3E. The End Flag is a carriage return, hex 0D.
The Node address is a two byte hexadecimal ASCII value in the range 00
through FF. Addresses F0 through FF are reserved. The command byte is
a single ASCII character. The Data field is of variable length and contains
ASCII characters as well. The data may not contain the '>' character. The
checksum is a two byte ASCII hexadecimal field representing the modulo
256 sum of Node Address, Command Byte, and Data fields (excludes the
start flag). A master can issue a "??" in lieu of a checksum. The "??" is use-
ful for testing communications with a terminal emulator program. Always
calculate and send the actual checksum when writing a communications
application.
If the slave acknowledge message has data, the checksum is the modulo
256 sum of all characters preceding the checksum including the response
code
Command
Acknowledge
Acknowledge with data
Error with code
Function
Start flag
Two character Ascii hex node address
one character Ascii function code
Data field. Up to 240 characters of ASCII data.
Two character Ascii hex checksum; ignored if set to "??"
Acknowledge
Error
Error code
End flag, hex 0D.
Serial Communications | A-1