Ping # on SCB-68

[CKH]

Hello,

I am currently trying to sync up two computers via Digital I/O on my PCI-7340 thru SCB-68 to COM port on another computer. With these devices, I use the VI from labview find example, Write 1 point to digit line, to operate this synchronization. I'm just wondering if anyone has this similar set up and what pin on the SCB-68 do you use?

Thank you,

CKH

[Joseph-S]

Hi CKH,

For your wiring-related questions, please take a look at this document: http://digital.ni.com/public.nsf/allkb/68BE5D9959E42FC986256FFE004AAFF4. Are you are trying to use the DO lines to send recognizable serial commands to another PC? This is not a trivial task, as the motion card is not a serial device and you cannot use our serial drivers on this card. Essentially, you would be programming your own drivers in LabVIEW to do serial communication and you would be relying on software timing in LabVIEW to write the correct sequence of digital pulses to the COM port. I assume you are not running a real-time system, which means you will not get deterministic performance. However, I cannot really comment on whether or not you will get enough consistency with software timing to acheive a reliable serial communication protocol.

If software timing does not give you enough performance, one possibility, which would be using the hardware in a configuration not technically supported by us, is to use the PWM outputs of the Motion card (which can be clocked off the clock of your motion card) to provide more accurately-timed digital pulses to the COM port. You can access the example for this under the example finder - Hardware Inpput and Output > Motion Control > NI 73xx > Analog and Digital I/O > PWM Output.vi. Again, I do not know enough about serial communication to tell you whether or not you can achieve the required signals by using the PWM outputs alone, but I hope this gives you a starting point for more investigation. Let me know if you have any further questions.

EDIT: I just did some more research and unfortunately, you would have to have a differential signal to communicate with a COM port because they work on a +/- 5 logic level. Therefore, it looks like you will not be able to achieve this with the motion card alone.

[Joseph-S]

Sorry, the link in my post is broken. Please use this link http://digital.ni.com/public.nsf/allkb/68BE5D9959E42FC986256FFE004AAFF4. Sorry about that.