Rockwell Automation 1769-SM2 Compact I/O DSI/Modbus Communication Module - Manual (Page 77)

Understanding Explicit Messaging 5-13
RSLogix 500 Modbus RTU Master Read Message Example
Figure 5.10 shows an example Modbus RTU Master read message setup
screen. See Table 5.D for descriptions of the message configuration data.
Figure 5.10 RSLogix 500 Example Modbus RTU Master Read Message Setup Screen
In this example, Logic Status and Feedback are being read from a
PowerFlex 70 drive. N7:110 through N7:113 (note the send length is 8
bytes or 4 words) contain the command data where:
N7:114 through N7:116 (note the Receive length is 6 bytes or 3 words)
contain the response data where:
For additional information about Modbus RTU read messages for
PowerFlex 7-Class drives, refer to the 20-COMM-H Adapter User
Manual, publication 20COMM-UM009.
Data Word Example Value Description
N7:110 15 PowerFlex 70 node address
N7:111 4 Function Code – Read Input Registers
N7:112 0 Starting Register Address (30001)
N7:113 3 Number of registers to read
Data Word Example Value Description
N7:114 3855 Value for 30001 – Logic Status word
N7:115 0 Value for 30002 – not used
N7:116 8192 Value for 30003 – Feedback word