Rockwell Automation 1769-SM2 Compact I/O DSI/Modbus Communication Module - Manual (Page 74)

5-10 Understanding Explicit Messaging
Figure 5.7 RSLogix 500 Modbus RTU Master Message Setup Screen
Table 5.D RSLogix 500 Modbus RTU Master Message Configuration Data
This Controller Section Description
Channel Always use “Expansion Comms Port.”
Slot The chassis slot occupied by the 1769-SM2 module.
Port Always set to “2.” Note: This field was not configurable in earlier
versions of RSLogix 500.
Communication Command Always use “CIP Generic.”
Send (Data Table Address) Starting data table address of the Modbus command data.
Size in Bytes (Receive) Number of bytes of receive data. It is set to “0” for a Modbus write
message, and to the necessary length for a read message (greater
than “0”).
Send (Size in Bytes) Number of bytes of command data.
Target Device Section Description
Message Timeout Timeout delay in seconds. This value must be greater than the
Message Timeout configured for the channel in the module’s I/O
configuration.
Target Type Always use “Network Device.”
Net Addr The number of the channel (1…3) on the 1769-SM2 module where
the message will be sent. Note: This field was called “Channel” in
earlier versions of RSLogix 500.
Service Always use “Custom.”
Service Code (hex) Always use “4b.” This is the Execute Modbus service.
Class (hex) Always use “33F.” This is the Class number for the Modbus RTU
Master object.
Instance (hex or dec) Not used. Leave at “0.”
Attribute (hex or dec) Not used. Leave at “0.”