Interfacing Ladder Logic with Microprocessor based dedicated system

  • Thread starter Jyotirmoy Chatterjee
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Jyotirmoy Chatterjee

I have an RTU which has all the cards as in a complete PLC. Is there any ladder logic software that can be used for programming purpose ? The RTU processor card is designed around Intel's 80C188EB processor.

I should say that it is not a popular branded RTU. We are basically such a company that deals with process automation systems and we use embedded software technology. Now, we have one RTU that is being used in lots of projects. And we are trying to make one PLC using that hardware. So we require one software and that should be user friendly.

Here are the RTU details.

It consists of:

1. One CPU card: -
a. Processor: Intel 80C188EB
b. 128 kB RAM
c. 64 kB EPROM
d. Crystal Oscillator: 6.144 MHz
e. Serial port: RS232, Qty - 1

2. DI card: 16 Channel

3. DO card: 16 channel

4. AI card: 6 channel

5. Power Supply Unit: 24V DC, +-12V DC, 5V DC

These cards are connected with each other through backplane. Our existing back-plane can accommodate:

1 CPU card (1 spare slot is there for CPU card)
6 DI cards
3 DO cards
1 AI card

Provision is there for expansion. We use mostly RS232 and RS485 communication protocol.

We generally write programs in C, C++ and assembly languages. And our HMI is written in VC++. But these things are user specific and are not user friendly.

In broad sense you can take our existing system as a DCS, but user specific.

So my question is that, is there any software available in the market that can be interfaced
with our existing system ? If not, then how can we make our existing system a PLC ?

Thanking your for your reply.

Jyotirmoy Chatterjee
If you're happy with mnemonics, there's a mnemonics-to-C translator as part of the MAT LinuxPLC project. It's pretty simple, but it might do (or you can extend it).

Check out
It'll be easy enough to cut out all the MAT-specific parts and substitute whatever you need.

If you have any questions, I was the primary author of that module, so I'm probably the best person to ask...

Jiri Baum <[email protected]> the MAT LinuxPLC project at