Rockwell-automation 1769-SM2 Compact I/O DSI/Modbus Communication Modu Manual de usuario descargar pdf (Pagina 73)

Understanding Explicit Messaging 5-9

In Multi-Drive mode, any channel can be configured for Modbus RTU

Master operation to communicate with a variety of Rockwell

Automation or 3rd Party RTU Slave devices, such as PowerFlex 7-Class

drives with 20-COMM-H adapters. In the Multi-Drive ladder examples

provided in this manual, CH3 is used to communicate with a PowerFlex

70 drive.

The following Modbus Function Codes are supported:

The format of the Modbus command message data is:

The format of the Modbus response message data is:

The format of the message instruction is different for Modbus RTU

Master operation messaging. For RSLogix 500, format each message as

shown in Figure 5.7

and see Table 5.D for a description of the data

required in each field. For RSLogix 5000, format each message as shown

in Figure 5.8

and see Table 5.E.

Modbus RTU Master Operation Messages

Function

Code

Name Maximum

Bits/Word

Function

Code

Name Maximum

Bits/Word

01 Read Coils 512 05 Write Single Coil n/a

02 Read Discrete Inputs 512 06 Write Single Register n/a

03 Read Holding Registers 32 15 Write Multiple Coils 512

04 Read Input Registers 32 16 Write Multiple Registers 512

Word Name Description

1 RTU Slave Address The node address of the Modbus RTU Slave.

2 Function Code The Modbus Function Code to perform.

3 Starting Address The starting coil/register address in the Slave device.

4 Number of bits/words The number of coils/registers to read/write.

5+ Data Words Only used for write messages and contains the data

to be written.

Word Name Description

1+ Data Words Only used for read messages and contains the data

that was read.

1 2 ... 68 69 70 71 72 73 74 75 76 77 78 ... 203 204

Sin comentarios

Rockwell-automation 1769-SM2 Compact I/O DSI/Modbus Communication Modu Manual de usuario Pagina 73