Suggestions for setting up a new PXI system

[RPB_KIP]

Hi all,
We are planning to setup a PXI system for the computer control of our new experiment. I have few questions:

1. Our choice for analog output card is PXIe-6739. The datasheet mentions a maximum update rate of 1 MS/s if we use upto 16 channels after which it drops to 350 kS/s. But it also says this is the update rate if we use one channel per bank (1 bank = 4 channels as per pin-out). This card has 64 output channels, so 16 banks.

My question is, if for 10 banks I use one channel per bank and for renaming 6 banks I use all 4 channels per bank, can I have 10 fast channels with 1 MS/s update rate and 24 slow channels with 0.35 MS/s update rate?

2. Our choice for digital I/O card is PXIe-6537. The maximum TTL voltage it can generate is 3.3 V. Would standard TTL devices (of 5 V) respond to this 3.3 V? OR is there a way to pull-up 3.3 V to 5 V (the easiest way, and not by myself soldering a bank of amplifiers.)?

3. Does NI provide any PXIe/PXI compatible card which can produce a variable frequency time-base (clock) under hardware timing?? I would like to stress hardware timing for precision timing. A similar third party solution is like PulseBlasterESR-CompactPCI (LINK).

4. Are there any BNC breakout boxes for PXIe-6739 and PXIe-6537. The screw terminal ones are the only compatible I know, but we want BNC breakout boxes for these cards if available.

Thanks.

[crossrulz]

2. You can give this a try: SparkFun Logic Level Converter

3. You might want to give the Arbitrary Waveform Generators a look.

[JÞB]

There is no one solution.   That is why several different devices are available and in several different form factors.   

Without detailed information about you system level needs you will only get general information.   Sometimes you should just call a partner to dive deeper into your needs than even a NI sales rep can offer.

NI does offer a listing of Alliance partners with information about their expertise. 

[Nathan-M]

1. "...can I have 10 fast channels with 1 MS/s update rate and 24 slow channels with 0.35 MS/s update rate?"

All channels must operate at the same rate if they're being used at the same time. You can run 10 channels at 1MS/s, and then switch to the other 24 channels at a lower rate. But if you'd like a mix of fast and slow channels at the same time then you should get a second module.

2. "Are there any BNC breakout boxes for PXIe-6739 and PXIe-6537"

No, you'll need to go full custom for that. Many NI Alliance partners make connection accessories like this. For the Digital card, I'm struggling to even find a reason why you'd want each DIO line on a separate BNC cable. Most uses for high speed digital like this are pairing many lines together into some kind of communication bus that would use its own custom cable + fittings.

Seems like you should give your local NI office or partner a call and have this conversation with them. 

[RPB_KIP]

@ crossrulz, thanks for mentioning SparkFun Logic Level Converter.

Well I agree with Arbitrary Waveform Generators answer in principle but it does not make me happy. I will try to give a logical point later. Also they have very less number of output channels.

[RPB_KIP]

@ Nathan-M, we want each DIO line on a separate BNC cable because they go to devices in different parts of the lab. For e.g. DIO 1 might give a trigger to a driver circuit for magnetic field and DIO 2 controls a camera trigger. These are common requirements in our experiments. We would club DIOs into a bus if they went to same device (or nearby devices??).

You also gave me good insight into update rate for channels. Thanks !

[Lysandros]

Hello

a few remarks to your topic:

• Since you generate many output signals, you should verify that the respective PXI card can hande the current draw to the signal sink. If the equipment, where the PXI outputs are heading has a small input impedance, chances are, that the current draw is pretty high.
• I dont't use BNC breakout boxes, but a PXI-6363 witha SCB-68A instead. I have heard that hese BNC breakout boxes are not very reliable, but I may be wrong.

Best wishes