Multi Rs232 connections

[fishingman]

Hi,

I developed a small test bench her equipments controlled by RS-232. The test will be done with TestStand and LabWindows. I want to use multiple ports RS-232, which communicate with Labwindows (DLLs). I want to know if is possible to keep these connections open simultaneously, or can not do that. If we can do that, Do you recommend this method or it's better to open and close a connection every time I order equipment.

Thanks

[Wolfgang · Accepted solution]

Hi,

I have a setup with 32 serial ports (via NI boards). Typically, all available instruments are communicating with the software, timer controlled (reporting their status on a 10-60 seconds time scale). This should answer your first question: yes, you can have several ports open simultaneously.

Concerning your second question: In my application, ports are kept open until the corresponding instrument is shut down. However, I can not answer if this is better or worse than reopening the port every time...

Hope it helps a bit,

Wolfgang

[fishingman]

Thanks,

I will test that and if i have any another question i will ask.

Many Thanks

[ebalci]

If you dont need to "talk" very often, you can OpenCom/CloseCom each time.

This may be even wiser if you need to do some debugging with HyperTerminal for example while running your TestStand application.

Otherwise, you will not be able to access the ports with another program until you terminate your test session.

But if your application requires a constant communication channel, then you have no option other than keeping the ports open all the time...

[fishingman]

Thanks for your response,

As I have said from the beginning, I have several materials (DMM, SCOPE, PowerSupply ...) are all controlled by RS232. So the test sequence every time communicates with one of these materials. My question is it's better to keep the communication open with all hardware and each time I access the requested material or I have to open and close communication with one material selected during the test sequence.

Thanks

[TurboMetrologist]

@Wolfgang, I'm curious are these RS232 computer cards with multiple ports or do you have a connection to an external board with 32 connections? What product are you referring to?

Thanks in advance! I had a similar question as to fishingman.

[Wolfgang]

Hi,

I am using two NI PCI-8430/16 boards, and one NI PCI-8431/8. Because these are not the only boards in the system (CAN, DAQ, GPIB,...), I am using an PCI extender - in that sense the cards are both internal and external

[TurboMetrologist]

Thanks!