connection of the pressure transmitter to the scxi-1102 module

[lalit]

Dear sir,

we have a differential pressure transmitter whose specifications are as follows:
Excitation:24 Vdc, output:4-20mA.(make: Cole-parmer instrumentation company)

now, we have a NI scxi-1102 and scxi-1520 module with corresponding terminal blocks.
Our question is how to connect this transmitter to the module and to which module? can we connect it to the scxi-1102? And for the excitation what we should do? please explain the detailed procedure for that.
As the excitation is 24 Vdc, i think we have to use 1102 and has to be excited externally.

Since, i m a mechanical engineer and don't have much knowledge of electronics, please explain all the details as simply as possible.

regards...

Lalit.

[bushman]

Since the device already has signal conditioning built into it, you don't need the 1520. You need an analog input card with a 250 ohm precision resistor across the input. that convrets the 4-20ma to 1-5 Volt. The input card would need to be configured for differential input.

[lalit]

can u please elaborate on how can i connect it to the SCXI 1102 module, if so it works.
what is the resistance that i have to connect and where in the circuit i should include it..

thanks in advance

lalit

[bushman]

I am assuming a couple of things here. They are:

The input you are looking at is a slow responding signal ie less than 2 hz. The 1102 has a built in 2 hz filter.
and or the transducer you are connecting to has a slow update rate.

You are using scxi 1300, 1303, or 1308 terminal block to connect to your chassis.
Channel 0 isn't being used.

That being said, in Max, set the gain to 1
input mode to differential
You can do the scaling in Max if you want to.That's what I typically do.
Linear scAle, 1 volt = 4 ma and 5 volt = 20 ma

On your terminal block, connect a 250 ohm precision resistor across Ch 0 in ( pin 96 & 64)
In series with your current loop ( cut the wire of the existing loop)
Connect one end to pin 96 and the other to pin 64.
Put a voltmeter across the input. red lead to 96, black lead to 64
If the reading is negative flip flop the wires. If positive, good guess.

you should be ready to rock and roll.

GB