Modbus addressing, Receive and transmit message formats – Comtrol Modbus TCP Quick Start User Manual

Page 58

58 - Configuring Read/Write Raw/ASCII Devices

DeviceMaster UP Modbus/TCP Quick Start: 2000477 Rev. G

Configuring Read/Write Raw/ASCII Devices

14. Set up the Application TCP Connection Configuration settings:

•

If no application socket interface is required, leave all application socket interface settings at defaults
and the application Enable option is not selected.

•

If an application socket interface is required, see

Application Socket Configuration

on Page 67.

15. Scroll to the bottom of the page, verify that Reset Port and Save in Flash are selected, and click Submit.

Modbus Addressing

The DeviceMaster UP socket port data addressing used for slave modes:

Receive and Transmit Message Formats

The format of received serial data sent to or returned to the PLC:

General requirements:

•

The memory area must be defined in 16 bit words and large enough to handle the largest serial packet
plus two words for the produced sequence number and data length parameters.

•

The Maximum Rx Data Packet Size must be set large enough to accept the largest possible packet.

For large received data packets over 246 bytes (This may be less for your PLC):

•

The Rx (To PLC) Transfer Mode must be set to Master (Write to PLC).

•

The data will automatically be placed in continuous memory.

•

All data will have been transferred to the PLC when the sequence number is updated.

The format of the transmit serial data received from the PLC:

Socket Port Raw/

ASCII Addressing

Socket Port 1 Socket Port 2 Socket Port 3 Socket Port 4 Access Rule

Unit ID

254 (FF Hex)

254 (FF Hex) N/A

Receive Data Address

1000 (Base 0)

1001 (Base 1)

2000 (Base 0)

2001 (Base 1)

3000 (Base 0)

3001 (Base 1)

4000 (Base 0)

4001 (Base 1)

Read Only

Transmit Data Address

1300 (Base 0)

1301 (Base 1)

2300 (Base 0)

2301 (Base 1)

3300 (Base 0)

3301 (Base 1)

4300 (Base 0)

4301 (Base 1)

Read/Write

Name

Data Type

Data Value(s)

Access

Rule

Receive (DeviceMaster UP to PLC)
message data.

Structure of:

Produced data sequence

Data length (in bytes)

Data array

WORD

Array of
WORD

0-65535 (FFFF Hex)

1-2048 (Master Rx Mode)

0-246 (Slave Rx Mode)

0-65535

Read