Specifications

STB NIP 2311 Services
EIO0000000051 6/2010 119
When to Use the Server
The Modbus server is accessed by either a Modbus client or an I/O scanner service
and should be used to transfer plant information, commands, or other required data.
The Modbus server provides real-time data transfer or access to data reports that
are stored in its memory. The Modbus server answers any Modbus requests it
receives. No additional configuration is necessary.
Any device that needs to exchange plant status, commands or data with other
devices should implement a Modbus server. A device that implements the server
can respond to requests sent from Modbus clients and make its internal I/O and data
available to remote devices for reading and control. The device may be an I/O
module, a drive, a power meter, a circuit breaker, a motor starter, or a PLC.
I/O modules are good examples of devices that implement a Modbus server service.
As servers, input modules let other control devices read values from them, and
output modules let control devices write values to them.
A PLC system implements both client and server services. The client service
enables the PLC to communicate with other PLCs and I/O modules; the server
service enables it to respond to requests from other PLCs, SCADA, HMIs and other
devices. Devices that do not need to respond to data transfer requests should not
need to implement a server service.