The jModbus Project - Citect Example

The following pages shows the setup and trend screen from a Citect project that talks to a TINI to read temperature values from DS18S20 chips via a ModbusTCP link. This citect project is located in the examples/citect directory of the distribution, called modnet.zip.

A basic knowledge of Citect is assumed. This project has 1 IO Server (IOServer) and 1 TCPIP board (Board1).

The ports are setup as shown below from the Citect Project Editor. Of particular note is the special options field that contains the string "-I159.111.194.61 -P502 -T" that specifies the IP address of the port with -I flag, the port number with the -P flag and the -T flag to indicate that a TCP connection is to be used, as opposed to UDP.

The devices are setup as shown below from the Citect Project Editor. This simply specifies that the MODNET (ModbusTCP) protocol is to be used to communicate with the device.

The variables are setup as shown below from the Citect Project Editor. This shows that the variable is being read from the 3xxxxx range (input registers) and the scaling that is used to convert between the UINT value used read from the DS18S20 chips to a decimal degreese celcius value.

This project also included a trend screen of the the 8 sensors attached to the two TINIs. A sample from the trend screen is displayed below.