Rockwell-automation 1769-SM2 Compact I/O DSI/Modbus Communication Modu Instrukcja Użytkownika Pobierz pdf (Strona 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

1 2 ... 72 73 74 75 76 77 78 79 80 81 82 ... 203 204

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Rockwell-automation 1769-SM2 Compact I/O DSI/Modbus Communication Modu Instrukcja Użytkownika Strona 77