Modbus Management Support And Memory Map - RuggedCom RMC30 User Manual

Appendix D. ModBus Management Support and Memory
Map
Appendix D. ModBus Management Support and
Memory Map
ModBus management support in RuggedCom devices provides a simple interface for
retrieving basic status information. ModBus support simplifies the job of SCADA (Supervisory
Control And Data Acquisition) system integrators by providing familiar protocol for the retrieval
of RuggedCom device information. ModBus provides mostly read-only status information, but
there are also a few writable registers for operator commands.
The ModBus protocol PDU (Protocol Data Unit) format is as follows:
Function Code
RuggedCom devices support the following ModBus function codes for device management
through ModBus:
1. Read Input Registers or Read Holding Registers – 0x04 or 0x03, for which the Modbus
PDU looks like:
Request
Function code
Starting Address
Number of Input Registers
Response
Function code
Byte Count
Input Registers
*N = the number of Input Registers
2. Write Multiple Registers – 0x10:
Request
Function code
Starting Address
Number of Registers
Byte Count
Registers Value
*N = the number of Input Registers
Response
Function code
Starting Address
Number of Registers
Note that as RuggedCom devices have a variable number of ports, not all registers and bits
apply to all products.
ROS® v3.11User Guide
Data
1 Byte
2 Bytes
2 Bytes
1 Byte
1 Byte
N*X2 Bytes
1 Byte
2 Bytes
2 Bytes
1 Byte
N* x 2 Bytes
1 Byte
2 Bytes
2 Bytes
125
0x04(0x03)
0x0000 to 0xFFFF
0x0001 to 0x007D
0x04(0x03)
2 x N*
0x10
0x0000 to 0xFFFF
0x0001 to 0x0079
2 x N*
Value of the register
0x10
0x0000 to 0xFFFF
1 to 121 (0x79)
RMC30