PXI-6509 cable length

[mannyb]

I have a test setup where I am using a PXI-6509 with it's corresponding 2m cable and an SCB-100 connector block. After the connector block I have two more custom cable assemblies that attach to each other. Total cable length is 2m (6.5 ft. for SH-100 cable)+ connector block+ 5ft cable assembly (22AWG) + 4 ft. cable assembly for a total of 15.5 ft. When turning "on" a specified output I can see 5V at the end of the 5ft. connection (11.5 ft. from the card), when the last cable assembly is connected there is no voltage. All cables are continuous, there are no intermittent faults. Is there a length limitation for the output of a DIO card?

[Ali M]

Hello mannyb,

National Instruments provides recommended cables for your device of up to 2m.You can try different cable lengths, but since this has not been tested (especially using these custom 3rd party cables), we can't support/guarantee correct output from your card at the length specified. 

Best regards,

Ali M

Applications Engineer

National Instruments

[mannyb]

Thanks for the reply, but actually what I really want to know is if there is a length limitation past the 2m?, if a connector block is sold (NI product) for this card I am assuming that the use of wire to send these signals elsewhere is allowed, so the question is how far away can I go with the output set at 1 (TTL 5V) degrade to the point where it is unusable. After further testing I have found that 10 ft is acceptable but the question still remains as to how far can I go with these signals.

Thanks

[Ali M]

Hello mannyb,

There isn't a hard specified limit beyond the recommended 2m, as long as the signals still fall within this range; the card should be able to pick them up as TLL.

Best regards,

Ali M

Applications Engineer

National Instruments

www.ni.com/support

[kekin]

What is your end to end wire resistance......at least from connector block?

Which ground are you using as a reference to measure 5V at the other end? Have u tried using connector block ground?

[mannyb]

About 0.4 ohms, the ground reference I am using is the one from the card, I actually conducted some experiments to see how far I could drivethe 24mA max (as specified on the spec sheet) produced by the card at around 20 ft. the voltage drops considerably. The custom cabling that I have will work, I would not drive more than 20 ft.