How to build a current loop with cFP-1808 and analog input module AI-110?

[Clara G]

I am trying to build a current loop to measure temperature via and a resistance thermometer a transmitter that converts the signal to current. I am using cFP-1808 with the power supply PS-5 directly connected to it.

For the current measurement I am using AI-110 but I am having trouble with getting current in my loop. I have looked in he manual of the AI-110 module and am using the set up for a "loop with an external power supply", counting the PS-5 as external. That is to say, I have connected the negative transmitter terminal to Vsup on the AI-110, and the positive side to Vin. Now, however, I am stuck. I don't get any signal in my loop.

Can I use the PS-5 to power my AI-110 module or do I need to use another external power supply? In this case, how do I connect this?

Thanks for any help!

[AnalogKid2DigitalMan]

Does your current transmitter have it's own power supply and thus is able to output a current on it's own?

If so, then use Fig 6 in the manual (current source without external power supply) and use the PS-5 just to power the cFP-1808.

In max set up your channel for current measurement.

Hope this helps

-AK2DM

[Clara G]

No, my transmitter does not supply its own power, it just converts the signal. I was told that the PS-5 was able to give power to the loop through the AI-110 module, but perhaps this is not the case?

I also tried connecting an additional power supply (24V DC) to the C and V terminals in AI-110 but I still do not get any current through the loop. Is this perhaps a software problem?

The channel on the AI-110 is set to measure current (0-21 mA).

[AnalogKid2DigitalMan]

Clara G:

I overlooked that in your 1st post you were connecting the other end of the transmitter to Vin, you actually need to connect it to Iin on the AI-110.

Regarding the use of the PS-5 to power the cFp and supply power to the loop, I do not know if that will work or not.

Suggest that you switch over to Iin terminal and use the separate 24V supply to power the loop. If that works, them maybe try the PS-5 for both the cFP and loop power.

-AK2DM

[Clara G]

Oops, that was actually a writing mistake from my side. I did connect it to Iin fram the start.

I have tried with an external power supply to V and C on the module now, and it still doesn't work. I get a voltage over V and C but no current in the loop.

Do I have to give some command to cFP? I have tried just testing the channel and it says "successful", so I guess I get a connection, but I get 0.000 Amps as value back...

[AnalogKid2DigitalMan]

Can you attach the specs/data sheets for your thermometer and transmitter along with a sketch of how you have wired everything up? In MAX, you can also check the version of your software (Fieldpoint and MAX) along with the version of firmware on your fieldpoint. That information may be of use too. -AK2DM