Westermo RM-115S - Manual (Page 52)

115S Serial I/O Module User Manual
Page 52 June 2011
Appendix B. Modbus Functionality
Table B-1 specifies the maximum query and response data parameters for the 115S
modules. See the Gould Modbus Protocol Reference guide (PI-MBUS 300 Rev B) for
more detail.
Function
code Description Maximum Data Size
1,2 Read coil / input status 1160 coils / inputs
3 Read holding (output) registers 145 registers
4 Read input registers 145 registers
5 Force single coil 1 coil
6 Set single register 1 register
7 Read exception status 8 coils
8 Loopback test N/A
9,10 NOT SUPPORTED NOT SUPPORTED
11 Communications event counter N/A
12-14 NOT SUPPORTED NOT SUPPORTED
15 Force multiple coils 1160 coils
16 Set multiple registers 145 registers
17-255 NOT SUPPORTED NOT SUPPORTED
Table B-1: Supported Modbus functions and limitations for 115S modules.