Download Modbus - PLC Simulator

This free protocol simulator was originally designed to allow testing of modbus master devices over serial, hence the name: Why is it called MOD_RSSIM? Because it started out as a modbus RS232 simulator - but it grew as all applications do, and even after adding TCP/IP support the name still stuck. MOD_RSSIM also allows itself to be used as a "virtual" PLC for comms testing, training and limited use as a source-code resource. Please download it to try it out, if it works for you, about 45 minutes later you will get a nag-screen, either Mail me, or use my free registration-key request screen at the bottom of the page. The sim carries on working after the nag-screen, it just gets tedious clicking on the "OK" button

- Download the simulator.
- Run it, and select TCP/IP or serial protocol.
- If you want serial, you can try using com0com (see the links page) to create a local loopback, and skip the serial cable.
- Select your serial port from the settings dialog (or if TCP/IP, simply point your HMI/SCADA to the local IP address) and Connect.
-Next you can click on the "Comms" button in the bottom-right to see the state of the communication link to see if your master is trying to connect and talk to the simulator already.
- Now go and look at your scada/hmi, if it's not already talking, go into your drivers and make sure they are started (in most cases no license will be needed from modbus protocol in your scada simply because it is so popular for verification), and if still not talking, look at your own communication logs.
- Unless you are doing something wrong, you should have zeroed values in the SCADA. Now for some fun..
- ...more Steps to follow.