Rockwell Automation 1755-OF8 GuardPLC Controller Systems - Manual (Page 271)

Publication 1753-UM001C-EN-P - March 2010 271
Communicate with ASCII Devices Chapter 21
For example, this string requests the first two variables from the slave.
ASCII Slave - Controller Response
If the controller receives a request from an ASCII master, it responds
in this format (each character is one byte).
Start Sign Destination Source Function Code Start Address Number of
Variables End Sign
^ 15 01 R 00000 002 &
Start Sign Destination Source Function
Code Start
Address Number of
Variables Number of
Characters Data End Sign
1 char 2 char 2 char 1 char 5 char 3 char 4 char maximum
10000 char 1 char
Component Description
Start Sign identifies the start of a message
^ character
Destination unique master address (requester)
01…99
Source unique slave address (GuardPLC controller)
01…99
Function Code r character identifies data sent by slave
E identifies error with master request
Start Address data start address for characters to read (offset)
00000…65535
Number of Variables number of variables to read and send back to master
000…999
Number of Characters number of characters in the data string (This includes
the “/” delimiter but not the “&” termination character.)
0000…9999
Data data characters
End Sign needed to recognize the end of a message
& character