Rockwell-automation 1769-SM2 Compact I/O DSI/Modbus Communication Modu Instrukcja Użytkownika Pobierz pdf (Strona 78)

5-14 Understanding Explicit Messaging

RSLogix 5000 Modbus RTU Master Write Message Example

Figure 5.11 shows an example Modbus RTU Master write message setup

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

Figure 5.11 RSLogix 5000 Example Modbus RTU Master Write Message Setup Screen

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

PowerFlex 70 drive. The CH3_MSG1_REQ array (14 bytes = 7 words)

contains the command data where:

A Destination element is not needed for a write message because no data

is returned.

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

CH3_MSG1_REQ [0] 15 PowerFlex 70 node address

CH3_MSG1_REQ [1] 16 Function Code – Write Multiple Registers

CH3_MSG1_REQ [2] 0 Starting Register Address (40001)

CH3_MSG1_REQ [3] 3 Number of registers to write

CH3_MSG1_REQ [4] 18 Value for 40001 – Logic Command word

CH3_MSG1_REQ [5] 0 Value for 40002 – not used

CH3_MSG1_REQ [6] 8192 Value for 40003 – Reference word

1 2 ... 73 74 75 76 77 78 79 80 81 82 83 ... 203 204

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Rockwell-automation 1769-SM2 Compact I/O DSI/Modbus Communication Modu Instrukcja Użytkownika Strona 78