10-05-2008 08:03 PM
Hello,
We are using an analog (NI-PCI-6723) and digital (NI PCI-DIO-32HS) output card to control our experiments, where the timing is controlled by the clock of the analog card, which drives the digital card over the RTSI bus connection.
We have a new device in our experiment, which is controlled through command lines over a RS232 line.
My question is, how can I use the clock of the analog card to time these commands over the RS232 line (maybe by using the RTST bus..?) Kind regards,
Erik
10-06-2008 05:21 PM
Hi Erik,
Are you looking to synchronize the start of the message with the start of an acquisition? Both National Instrument's and you computer's serial port are designed to communicate asynchronously. You can export the RTSI bus where you could use that signal to trigger the start of a send or receive sequence, but the start of the communication will not be fully synchronized since it will be timed with software.
National Instruments
10-07-2008 02:09 AM
Hi Caleb,
Thanks! Can you tell me how to export the RTSI bus, so I can send the command after a certain amount of clock cycles?
I would preferably use the RTSI bus as a input-clock, where I will count a certain amounts of clockcycles and then send the command. Maybe it's not perfectly synchronized, but it might be good enough. Can this be done?
Cheers,
Erik
10-07-2008 05:33 PM
10-07-2008 07:25 PM
Hi Chris,
Thanks! I know how to sync two NI devices (the clock of an analog card drives a digital card using the RTSI bus in our case) and we use this to sequence our experiment. What I would like is to add is the serial port into this sequence.
So I would like to send a command over de serial port at a specific time, determined by the clock of the analog card. So can I somehow do that using the RTSI bus? Do I perhaps need to buy, for example, the PCI-485 cards?
A (dodgy) way is to 'solve' this is to start the sequence together with a timed loop, determined of course by the clock of the computer and therefore leading to inaccuracies. I'm sure there must be a better way.
Thanks for you help,
Erik
10-08-2008 11:24 AM