IDEC MicroSmart Pentra - Manual (Page 89)

W EB S ERVER CPU M ODULE U SER ’ S M ANUAL FC9Y-B1278 9-1
9: M
ODBUS
TCP C
OMMUNICATION
Introduction
This chapter describes the Modbus TCP communication of the Web server CPU module. The Web server CPU module can
be used as Modbus TCP client/server. The Web server CPU module can communicate with the devices supporting
Modbus TCP communication on the network.
Modbus TCP Communication Overview
The Web server CPU module can be used as Modbus TCP client/server. Modbus TCP server and client of the Web server
CPU module can be used simultaneously.
When the Web server CPU module is configured as Modbus TCP server, Modbus TCP client devices can access the Web
server CPU module and read and write the data. A maximum of eight server connections can be configured as Modbus
TCP server. If all eight server connections are configured as Modbus TCP server, a maximum of eight Modbus TCP client
devices can access and communicate with the Web server CPU module simultaneously.
When the Web server CPU module is configured as Modbus TCP client, the Web server CPU module can access Modbus
TCP server devices and read or write the data. A maximum of three client connections can be configured as Modbus TCP
client. The Web server CPU module can communicate with multiple Modbus TCP server devices per a client connection.
For the specification and configuration of Modbus TCP client, see “Modbus TCP Client”. For the specification and
configuration of Modbus TCP server, see “Modbus TCP Server” on page 9-7.
Modbus TCP Client
Modbus TCP client communication settings and request tables for Modbus TCP servers can be programmed using the
WindLDR Function Area Settings. The Web server CPU module communicate with the Modbus TCP servers according to
those settings.
Communication with Modbus TCP servers are performed in synchronism with user program execution, and the
communication data are processed at the END processing in the order of request numbers specified in the request table.
Modbus TCP Client Specifications
*1: Specifies the period of time before receiving a response frame from a server.
Parameter Modbus TCP Client
Number of Remote Hosts 255
Slave Number 1 to 247
Maximum Number of Servers 255
Receive Timeout *1 100 to 25,500 ms (in increments of 100 ms)