Modbus Communications Procedure - Omron E5AN Communications Manual

SECTION 5
Modbus Communications
Procedure
Read this section if you are to communicate using the Modbus format.
5.1
5.2
5.3
5.4
Data Format.................................................................. 5-2
Command Frame................................................... 5-2
CRC-16 Calculation Example................... 5-3
Response Frame ................................................... 5-4
Normal Response Frame ......................... 5-4
Error Response Frame............................. 5-4
Error Codes ........................................................... 5-5
No Response............................................ 5-5
Function List ................................................................. 5-6
Variable Area ................................................................ 5-7
Addresses ................................................ 5-7
Number of Elements................................. 5-8
Set Values ................................................ 5-8
Detailed Description of the Services............................. 5-9
Variable Read, Multiple ......................................... 5-9
Variable Write, Multiple........................................ 5-11
Variable Write, Single/Operation Command........ 5-14
Echoback Test..................................................... 5-20
5-1