Channel in Module FP-AI-100 reads incorrect current value

[Jorg]

I have a field point FP-1600 and two FP-AI-100 modules. I have problems with two channels in one of the modules. The first channel reads the current loop with a offset of at least 4 ma, so if the current in the loop is 6 ma, measured with a digital multimeter, the field point explorer outputs a current of 10 ma. The second channel, in the same module, indicates always that current is out of range, in despite of the current that is actually in the loop.

[AndreOliveira]

Hi,

Try to measure the input impedance between the terminals Iin and COM for the misbehaving channels, this impedance should be of 100 Ohms.
If the impedance value is not the expected one, the channels might have been damaged somehow. Your module has an overcurrent protection of +/- 30 ma , so any value beyond this will possibly damage the channel, even current spikes might damage the channel.

If you verify the impedance value is not the expected, you can go ahead and contact National Instruments to repair the unit. For future reference please look a the following KnowledgeBase article :

http://digital.ni.com/public.nsf/websearch/561CF161D99BAD0986256BE2007A457E?OpenDocument

The article describes an external circuitry that can be used to protect t
he channels from any possible spike.

Best Regards

Andre Oliveira
Applications Engineer
National Instruments

[ARNOMUCH]

bonjour ce lien est incorrect, pouvez vous l'actualiser, merci