Thermo Ramsey Micro-Tech 3000 Series - Chapter 3.8 Modbus Protocol; Modbus Protocol Register Read

Serial Communications 3104
REC XXXXX 3-30
DLE (10H)
ETX (03H)
BCC (XXH)
DLE (10H) Æ
Example :
The Host wants to receive the LOW RATE SET (address 78 hex).
HIGH WEIGHT SET : 100.0 %
HOST (PLC)
SLAVE (3104)
02H Æ
Å 10H
00H 00H 45H 44H
00H 78H 00H 02H
FFH FFH 10H 03H
6BH Æ
Å 10H
Å 02H
10H Æ
Å 00H 00H 00H 00H 42H C8H
00H 00H 10H 03H 99H
10H Æ
3.8 Modbus
This protocol has been implemented as described in : - “Gould Modicon Modbus
Protocol” – Reference Guide – November 1993 – Rev.A (Gould Inc. Programmable
Control Division).
NOTE: Only a subset of the protocol has been implemented, as described in this
chapter.
3.8.1 Read Register
QUERY
Address xxx
function 03H
add.hi xxx
add.lo xxx
n.data hi xxx
n.data lo xxx
crc16 lo xxx
crc16 hi xxx
REPONSE MESSAGE
Address xxx
function 03H (83H in case of error)
byte cnt xxx
data MSB xxx
… xxx