Hi Guys, I am working on a project to replace an old honeywell PLC and HMI. The HMI failed and is not available anymore, PLC still works but without control??

It is an area with a connected smaller and bigger room, the small room has one ventilator, and the bigger room has 3 ventilators. The ventilators are controlled by inverters, the inverters are speed controlled by simple 0-10 Volt signals, the minimum speed is 50%, so the control range is 5-10Volt.

At the same time, the rooms need to keep an overpressure from 30Pa. This is measured by a differential pressure sensor with analog output 0-10Volt or 4-20mA, (i need to identify this still).

The two rooms have a temp sensor with 0-10 Volt sensor with 0-100 Cel range, also to be confirmed.

I will use a logo PLC with multiple extension modules to control the signals.

The first setup for the software, i am using multiple PI controllers and math blocks. I still need to include a TDE display, but this has low priority for me.

My question during simulation, my program works, i am only not 100% sure on the way that i combined the PI functions in math blocks, and as a setup it becomes complex. Do you have another solution or do you think i am on the correct path?

Thanks for any support in advance.

@Quirin, Thanks for your example, that is indeed a simpler setup. During testing from my original idea, it never went above 1000. So it may not be a problem anyhow, the inverters have 100% at 10 Volt. I will check if i incorporate your solution.

I still have to include the normal start/stop and alarm handling in case of failure, i will use a TDE for front panel control and information and then using the function keys to start stop (this is only done during maintenance), on the TDE i will show the running frequency from the inverters, i found an analog output that has the frequency range as 4-20mA, so perfect for the TDE information.  One interesting item to solve is that two inverters in case required (smoke/fire) need to work in reverse this signal i receive as a DI and i need to control the inverters by a signal contact in case of reverse operation, only i can not change over directly, i first need to stop wait for stopping and then reverse and start to 100%. That is for tomorrow, i expect the ordered material to receive this Monday so then i will need to build up and test life.

Thanks for the support