232
saia-pcd.com
3330
PCD3.M
Modbus ASCII / RTU
Communication & Interaction
2.6.3
Modbus
Modbus is a communication protocol based on a master/slave or client/server architecture. It is widespread and supported by many
manufacturers and devices. In many cases, Modbus is therefore the common denominator for transferring data between different devices
and systems.
Modbus with Saia PCD®
Modbus comes in three forms:
Modbus ASCII
data are transmitted in ASCII format via serial
interfaces (RS-232, RS-485).
Modbus RTU
data are transmitted in binary format via serial
interfaces (RS-232, RS-485).
Modbus TCP
data are transferred in TCP/IP or UDP/IP packets
via Ethernet.
Supported Modbus function codes
1 Read Coils
2 Read Discrete Inputs
3 Read Holding Registers
4 Read Input Registers
5 Write Single Coil
6 Write Multiple Coils
7 Write Single Holding Register
8 Write Multiple Holding Registers
Convenient Fulpa FBoxes or CSF commands are available for configuring and
programming the exchange of data.
With the integrated automation server, external systems can also be easily
linked to master Web+IT automation environments via Modbus.
Application example
The Modbus protocol is supported in the Saia PCD® COSinus
operating system by all Saia PCD1.M0_, Saia PCD1.M2_,
Saia PCD2.M5_ and Saia PCD3 controllers. Client and server
functionalities are available for all types of protocol.
Ethernet interfaces and serial interfaces (RS-232 and/or
RS-485) are already included in the PCD controller basic de-
vices. Additional plug-in interface modules can be used to
operate up to 9 serial Modbus interfaces per PCD system.
Number of connections
Each Saia PCD® system is able to establish up to a maximum
of 26 connections. Of these, the Saia PCD® controller is able
to use a maximum of 10 for client connections. The remain-
ing connections can be used as server connections to the
same Saia PCD® controller.
Media Mapping:
adjustable by the user
Mapping Areas:
max. 10 per UID
Number of servers:
max. 4 per PCD system
Number of unit IDs: max. 10 per PCD system
Number of channels: max. 10 per PCD system
Modbus TCP
Ethernet
PCD2
PCD1
PCD3
