Rockwell-automation 1769-SM2 Compact I/O DSI/Modbus Communication Modu Manual de usuario descargar pdf (Pagina 76)

5-12 Understanding Explicit Messaging

RSLogix 500 Modbus RTU Master Write Message Example

Figure 5.9 shows an example Modbus RTU Master write message setup

screen. See Table 5.D for descriptions of the message configuration data.

Figure 5.9 RSLogix 500 Example Modbus RTU Master Write Message Setup Screen

In this example, Logic Command and Reference are being written to a

PowerFlex 70 drive. N7:100 through N7:106 (note the send length is 14

bytes or 7 words) contain the command data where:

Note the Size in Bytes (Receive) is set to “0” because no data is returned

for a write message.

For additional information about Modbus RTU write messages for

PowerFlex 7-Class drives, refer to the 20-COMM-H Adapter User

Manual, publication 20COMM-UM009.

Data Word Example Value Description

N7:100 15 PowerFlex 70 node address

N7:101 16 Function Code – Write Multiple Registers

N7:102 0 Starting Register Address (40001)

N7:103 3 Number of registers to write

N7:104 18 Value for 40001 – Logic Command word

N7:105 0 Value for 40002 – not used

N7:106 8192 Value for 40003 – Reference word

1 2 ... 71 72 73 74 75 76 77 78 79 80 81 ... 203 204

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Rockwell-automation 1769-SM2 Compact I/O DSI/Modbus Communication Modu Manual de usuario Pagina 76