Current and Voltage Inputs on Input One Card

[dladd29l]

I'm very new to AB PLC's and very cautious when it comes to hooking new stuff up (hoping to avoid blowing up any I/O cards, haha).

Anyway, we are altering our testing lab where I am currently using an ControlLogix 5571 to control several valves and cycle through a series of pressure events.

Previously the only thing on our analog input card (1765-IF8) was a pressure transducer. From what I can tell, it's a single wire current setup. (All of the iRTN's are daisy-chain jumpered to the the RTN. The transducer has the DC ground tied to the same source as the RTN and the other wire tied to position IN-0). It's programed for 4-20ma

I am needing to add a linear transducer to one of our valves (it has already been purchased and was provided to me). After speaking to the manufacturer, it's a potentiometer. I provide it power in and sends varying power out on the signal wire based on position.

My 1756-IF8 card will accept 0-5v, 0-10v, and 4-20ma signals, however I am not clear if i can mix and match current signals and voltage signals on the same card and that's why I'm here.

If I can, will having the existing transducer and the new one on separate power supplies (24V and 5V) introduce problems?

Thanks!

 

[dladd29l]

Bueller, Bueller?

Haha, was my question too simple or not explained well enough?

 

[Saffa]

Not that familiar with controlLogix but having mixed current and voltage outputs on the same card is not an issue for the micrologix range so i doubt it will be for control logix.

Generally if there's an analog common terminal on the card then all analog input "negatives" should be at a similar potential to this common. This will be the case if you tie the zero volts of your 24V and 5V supplies together.

The manual for the analog input card will have more details, habe you read it?

 

[Geospark]

Yes, you can mix current and voltage inputs with this analog module...

ID: QA4854 | Access Levels: TechConnect
1756-IF8, 1756-IF16: mix of voltage and current inputs

...so long as you wire both types as either single ended or differential, but not a mix of the two wiring types.

See also here...

ID: QA24988 | Access Levels: Everyone
1756-IF8, 1756-IF16: Mixing Single-Ended and Differential Inputs

...as it mentions, the data format selected for the module profile in the software (RSLogix 5000/Logix Designer) dictates how the data for the entire module is handled...

Single ended - all analog points are available for the module
Differential - half the analog points are available for the module

If your pressure current transducer (IN0) is wired single ended then you must also (use) wire your linear voltage transducer as single ended.

...will having the existing transducer and the new one on separate power supplies (24V and 5V) introduce problems?...

Wire the DC ground for the linear transducer to the iRTN for the input assigned. As all iRTN are jumpered to RTN, this will create the common ground for all single ended devices connected to the module i.e. both power supply DC grounds are now common.

Regards,
George

 

[dladd29l]

Great, Thank you both for the information!

I had come across the line about not mixing single ended and differential in the manual, but I had not specifically found anything about mixing and matching current and voltage inputs. Trying not to let the smoke out of this thing on accident. lol

Thanks Again!