Analog module 1746 IF4 AB

joaco1993 · May 19, 2016

Hello guys, i have a question , what happens if I connect the module directy to my powersource , will it fault the plc ?? I mean of course the current will be greater than 20mA, thats why im asking,

image attached,

thanks!

bernie_carlton · May 19, 2016

If the input switches were set to voltage then there won't be any problem as the voltage mode input protection is 30VDC.

If they were on current then that channel will probably be damaged as the protection shows 32ma.

The isolation to the rest of the system is only 30VDC so the inputs are not optically isolated from the backplane. Take care. If a higher voltage then you may fry more than just the card.

joaco1993 · May 19, 2016

Bernie thanks for answering, im asking because of the following:

I have a level transmitter which has a label that looks like the attached img.

And i connected it as the image shows but didnt work, it showed a value of 12 , so I connected it the other way, see image, and then I got a reading of 20.000 which seems ok,

But i cant figure out why the second option is ok,

Mickey · May 19, 2016

The "Did not work" option is the wrong polarity on the loop powered transmitter.

I got a reading of 20.000 which seems ok

Only if the level is at its upper limit and you have the module setup for current.

joaco1993 · May 19, 2016

why is it wrong ?? if it says 4-20 mA , that wire (brown) shouldn go to the In + ??

Nope, 20.000 and it wasnt at the top, if it was at the top it should have read 32.000 and something right ?

ASF · May 19, 2016

Google "loop powered transmitter" and do some reading up on how they work.

Here's a good illustration:

joaco1993 · May 19, 2016

OK, but if the brown wire says 4-20mA shouldnt it go to the In+, and the other one that says 0-30Vdc shouldnt go to the - of the power supply ??

Mickey · May 19, 2016

Electron flow (-) minus to (+) plus.
Starting at the power supply leaving the minus side flow through the module - to + then through the transmitter - to + then back to the + side of the power supply.

Nope, 20.000 and it wasnt at the top, if it was at the top it should have read 32.000 and something right ?

Then something is wrong. Check to see how the transmitter is calibrated
4ma = 0 ?
20ma = ??

How is the analog card setup voltage or current.

joaco1993 · May 19, 2016

First) you say the DID WORK solution is wired ok ?

second) The raw value for 4mA is 6000 and something and 20mA is 32000 and something

so a value os 20000 it seems ok to me..

The analog card is set to current, all channels

bernie_carlton · May 19, 2016

The names would make more sense if the sensor is used in the minus side.

Pwr source +

Module +

Module -

Sensor +

Sensor -

Pwr Source -

Or use ASF's drawing, move the sensor to the lower line while rotating it 180 degrees..

Mickey · May 19, 2016

First) you say the DID WORK solution is wired ok ?

Yes

second) The raw value for 4mA is 6000 and something and 20mA is 32000 and something

Those values will depend on how you have the card configured (software configuration)

Post your .rss file and we can take a look . Zip the file first.
Tell us which card if more then one and which channel.

Analog module 1746 IF4 AB

Are you sure this is the right catalog number?
There is a 1762-IF4 and a 1746-NI4.

joaco1993 · May 19, 2016

Bernie sorry but didnt understand what you mean..

Mickey i dont have the file here but this is how i configure it:

In the IO configurations where I added the module, i set it for 4/20mA current. It is a 1746 if4. and set raw/proportional

I read in the manual that for 4 mA = 6241 and 20 mA = 31206. So if the tank is some how in the middle an input of 20000 is okay to me, why you dont think the same ??

Anyway my mainproblem is understanding the wiring, cant understand why the vendor puts 4-20mA in the brown and that cable you have to connect it to the power source and not to the input module..

Sorry if this is too basic! dont get mad! haha

Mickey · May 19, 2016

Then something is wrong. Check to see how the transmitter is calibrated
4ma = 0 ?
20ma = ??

I meant how its set up in engineering units.

joaco1993 · May 19, 2016

Mickey said:
I meant how its set up in engineering units.

Oh.. 4mA - 0meters
20mA-3meters

But the 20000 value is the raw input value, then I have a SCP instruction to scale the input..

Mickey · May 19, 2016

I read in the manual that for 4 mA = 6241 and 20 mA = 31206. So if the tank is some how in the middle an input of 20000 is okay to me, why you dont think the same ??

This would be ok.

You said..

And i connected it as the image shows but didnt work, it showed a value of 12 , so I connected it the other way, see image, and then I got a reading of 20.000 which seems ok,

I read this to be 20.000ma not counts(raw data)

Analog module 1746 IF4 AB

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