PAC RS232

[martin3885]

Hi,
I am about building small stand-alone control station for a vacuum appliance. There are some vacuum pumps, valves and one ion source to control. Most problematic is that some of these devices use RS232 interface. In my opinion the best option would be a PAC. My question is which modules should I choose to be able to communicate through RS232?

Martin

[Wayne.C]

Martin,

How many rs232 ports do you need?  NI cFP-2120 controller module has 3 rs232 ports and 1 rs485 port.  The Compact Field Point family is perfect for standalone applications and the serial ports are very easy to program using the NI-VISA functions.

[martin3885]

Hi,

thanks for your answer. Presently I need 4 RS232 ports. In the future it will be about 5 times more ports so the controller has to be so designed that I don't have any problems with extending it with new modules.

Martin

[Wayne.C]

That's a lot of serial ports for a PAC application.  Depending on the size of your program, one cFP controller is all you will really need to handle the processing.  Normally you would have one controller module mounted on a backplane with several I/O modules.  The problem is that there is not an I/O module available that has serial ports on it.  You only have what you get with the controller module. The cost of the controller modules will become prohibitive if you are only buying them for the serial ports.  

I have seen in the past external RS232 switches that could be addressed serially.  Something like that could be a more cost effective way to get all your ports.  Will you need to communicate with multiple devices simultaneously?

[martin3885]

So... that must I rethink it... Normally the devices don't have to be controlled simultaneously. The only situation when they all (probably) must be controlled simultaneously is the emergency stop. I will look into documentation, rethink the problem and come here back 🙂

Martin