New to Control Logix 1756-IF16

[Sevenfins]

As the title suggests, I'm pretty new to control logix. Well, what I am supposed to do is connect like 8-2 wire analog sensors to this card. From what I read the left side can be used to do analog signals. I don't quite understand the whole rtn thing at all. I'm trying to get 4 to 20 mA. Does this card supply the power or something? Can I just use the left side terminals for the source and drain? Sorry for the overload here. The previous engineer did a horrible job at setting this up.

 

[PreLC]

Hello Sevenfins,

Here is the manual for the AB IO Cards:
https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1756-um009_-en-p.pdf

Page 61 has the possible wiring types listed in it. From the attached image, seems like you'll need to provide your own loop power for 2 wire current measurement.

 

[I_Automation]

Yes, the module does not supply the power as some others do.


Even for the 4 wire example below it uses a user supplied power supply.

 

[Bit_Bucket_07]

The first thing you'll need to do is to determine whether you want to use the module in 16 channel single ended mode or 8 channel differential mode. How you'll wire the module depends upon this module configuration option. Single ended mode is more efficient, while differential mode provides better noise rejection. Configuring the module for single ended mode assigns one input amplifier to each channel, while configuring for differential mode assigns two input amplifiers to each channel.

All analog input modules measure voltage. To measure a current input, you must series the current loop through a 250 ohm resistor. The module then reads the voltage drop across that resistor. 4-20 mA = 1-5 VDC.

The RTN terminals are the common terminals for voltage inputs. For current inputs, you connect the instrument common to an iRTN terminal and then install a jumper between that iRTN terminal and a RTN terminal in order to place the module's built in 250 ohm resistor into the current loop and convert the transmitter output from a current input to a voltage input. The RTN terminals are all interconnected internally.

This module does not provide loop excitation power, so if you are using a 2 wire transmitter, you must provide an external loop excitation power supply.

 

[Sevenfins]

So, no matter what I will need to use the RTN? I think their thinking was that they would provide source whi h would go through say a temperature probe and then the common of the probe would enter through the input on the terminal. But you are saying I will need to have one end coming from channel 0 (2 on the block) and have the common go through the irtn and then that will be Jumpers to the rtn?

 

[Sevenfins]

Nevermind. I reread what you guys said and now I understand it. Thank you very much.