Startscan signal on PCI6071E DAQ cards

[joeyang]

Hi, everyone:

I am trying to use PFI7/STARTSCAN to synchromize two PCI-6071E daq cards in two PCs. I use VB to configure PFI7 line on the server DAQ card. The commend I used is "select_signal(1, ND_PFI_7, ND_IN_SCAN_START, ND_LOW_TO_HIGH)". I used a scope to monitor the output signal from PFI7. I found half cycle of the signal is zero. The other half cycle is 5V (is this correct signal?), including negative pulse from 5V to zero. Is it supposed to be positve pulses from 0V to 5V? Is there any switch on the DAQ card I should change?

I tested PFI7 on PCI-MIO-16E-1 daq cards using same program. This time, I got correct STARTSCAN signal with positive pulses. The MAX on the client PCs counted the pulses from PFI7 line

Can anyone help me? Thank you very much. I appreciate.

Sincerely

Joe

[sergesl]

hello Joeyang,

If you want to synchronize those boards, the correct thing to do is to route the sample clock through RTSI to the other device. If you have questions on specific functions, the Traditional NI-DAQ Function Reference Help in Start->All Programs->National Instruments->NI-DAQ.

The explanations below were taken from that document:

Example

To send a signal from your E Series device to the RTSI bus, set signal to the appropriate RTSI bus line and source to indicate the signal from your device. To send the analog input start trigger on to RTSI line 3, use the following call:

Select_Signal(deviceNum, ND_RTSI_3, ND_IN_START_TRIGGER, ND_LOW_TO_HIGH);

Example
To receive a signal from the RTSI bus and use it as a signal on your E Series device, set signal to indicate the appropriate E Series device signal and source to the appropriate RTSI line. To use low-to-high transitions of the signal present on the RTSI line 4 as your scan clock, use the following call:

Select_Signal(deviceNum, ND_IN_SCAN_START, ND_RTSI_4, ND_LOW_TO_HIGH);