In the last lesson, you would have viewed videos that introduced Modscan32 and how it would be used in testing communication to a Modbus slave device, in our case it was PLC B.
What I would like to show you in this lesson is a live Modbus Query / Response cycle taking place in real time between a Modbus master and a Modbus slave device, just like in the case of PLC A and PLC B. The challenge, however, is that we do not have a physical PLC A or PLC B to use to create an actual Modbus network and see the Query / Response cycle.
There is a way around this, however, and it is even better than having actual PLCs to work with. What I am going to show you how to do is to create a Modbus network within your PC/laptop. Sounds complicated? Well it’s simpler than you think.
What we are going to do is to download and install the sister application to Modscan32. It’s called Modsim32. Whereas Modscan32 works as a Modbus master, Modsim32 works as a Modbus slave. We will be connecting Modscan32 to Modsim32 using an application called Virtual Serial Port and we will see the simulation of two Modbus devices communicating in real time.
Once we set this virtual Modbus network up, I will take you through more troubleshooting tips and techniques.
So without further ado, please have a look at the YouTube videos below. Once you have a look at them, please don’t stop there. I want you to download all of the applications and try to copy exactly what I do in the videos.