Data Exchange. WAGO MODBUS Fieldbus Coupler RTU

WAGO-I/O-SYSTEM 750

750-316/300-000 Fieldbus Coupler MODBUS RTU

Function Description 75

7.3 Data Exchange

The MODBUS RTU protocol is used for exchange of process data for the fieldbus coupler 750-315/300-000 .

MODBUS RTU operates according to the master/slave principle. The master is a higher-level controller, e.g., a PC or a PLC.

The WAGO-I/O-SYSTEM 750 fieldbus couplers are slave devices.

The master requests communication. This request can be directed to certain nodes by addressing. The nodes receive the request and, depending on the request type, send a reply to the master.

The maximum number of simultaneous connections can not be exceeded. Existing connections must first be terminated before new ones can be set up. The Fieldbus

Coupler MODBUS RTU is essentially equipped with two interfaces for data exchange:

• the interface to the fieldbus (Master)

• the interface to the I/O modules.

Data exchange takes place between the fieldbus master and the I/O modules.

If MODBUS is used as the fieldbus, access is made to the data using a MODBUS function implemented in the fieldbus coupler.

7.3.1 Memory Space

Figure 39: Memory Areas and Data Exchange

Manual

Version 1.0.0