Dear all,

                    I am using IM 151 -8PN/DP CPU with analog input and output cards, Recently  i added one more 2AI I 4-20mA module 6ES7 134-4GB01 -0AB0.  I have two cases mentioned below

1. I connected 2 wire transmitter directly  to first channel of AI module and i am able to read the siganl to plc.

2.  I am using p & f Analog isolating barrier in between pressure transmitter and AI module for Ex proof reason. transmitter connected input side of Isolating barrier and AI module connected with output side of barrier.  the  barrier output  is source type and  my AI channel also generating 24volts for the field device,  i think  because of this reason i am not reading the siganl to PLC.

I uploaded isolating barrier data sheet.

please help to find some solution

Hello Dhinagaran

what i think, you should check your pressure transmitter. does it have terminal for power supply or it use the same signal line for power supply.

in case its the same, then connect the positive leg of transmitter with power supply positive and negative leg to the positive leg of isolation barrier and connect negative leg of isolation barrier with negative terminal of power supply.

either you can check the connection with supplying 4-20 ma source at the barrier input.

Regards

sanjay

dhinagaran.v

Dear all,

                    I am using IM 151 -8PN/DP CPU with analog input and output cards, Recently  i added one more 2AI I 4-20mA module 6ES7 134-4GB01 -0AB0.  I have two cases mentioned below

1. I connected 2 wire transmitter directly  to first channel of AI module and i am able to read the siganl to plc.

2.  I am using p & f Analog isolating barrier in between pressure transmitter and AI module for Ex proof reason. transmitter connected input side of Isolating barrier and AI module connected with output side of barrier.  the  barrier output  is source type and  my AI channel also generating 24volts for the field device,  i think  because of this reason i am not reading the siganl to PLC.

I uploaded isolating barrier data sheet.

please help to find some solution

 Could you please clarify following points?

1. Are you connecting both AI simultaneously?

2. Connect the AI with isolation barrier to first channel of AI module. Do you get the AI reading in PLC?

Have you confirmed the connection for correct polarity? i.e. terminal 7 of isolation barrier to terminal 2 in case channel 1 (6 in case channel 2) & terminal 8 of isolation barrier to 5 of channel 2 (1 in case channel 1)

Hello dhinagaran.v,

Unfortunately, the barrier you have has an active output. This will not fit for your 2-wire analog input module.

You have two options.

1- Add a new 4-wire analog input module (e.g. 6ES7134-4GB11-0AB0). I think this will be lowest cost.

2- Replace the P+F barrier with one that has sink output (e.g. KCD2-STC-Ex1).

You can find more configurable barriers other than P+F by some quick search(e.g. PR electronics).

Best regards,

H-H

H-H

Unfortunately, the barrier you have has an active output. This will not fit for your 2-wire analog input module.

You have two options.

1- Add a new 4-wire analog input module (e.g. 6ES7134-4GB11-0AB0). I think this will be lowest cost.

2- Replace the P+F barrier with one that has sink output (e.g. KCD2-STC-Ex1).

 Hello Experts,

Kindly explain the following idea:

Active O/P from the barrier (Source) connected to 4 wire analog I/P module(Sink)

Sink O/P from the barrier connected to 2 wire transmitter module(Source)

Hello Wago,

I thought it was clear. I hope you wouldn't get more confused by what follows.

Basically, you should understand the possible connections and terms of normal applications where transmitters are connected directly to analog input modules.

Active/source device (module) means that this device has a DC potential across its terminals.

Passive/Sink means this device doesn't generate any voltage across its terminals.

Two wire transmitter is a passive component (varies the mA in the loop according to measurement  but needs DC voltage to operate).

Two wire analog input module is an active module (has DC voltage across its terminals to supply 2-wire transmitters).

4-wire transmitter means it has separate two wires for power and and two wires for signals. The 4-wire transmitters will have (most likely) active 4-20mA.

You can't have two active components in a single side of the loop.

A two wire transmitter (passive) requires an active analog input module (2-wire analog input module).

A 4-wire transmitter (active) requires a passive analog input module (4-wire analog input module).

The barrier is a device that is used for transmitters in hazardous area (Ex barrier) or for higher isolation voltage (Isolator) between field and DCS/PLC.

The barrier acts like an analog input module for the transmitter and acts like a transmitter for the PLC.

Most of Ex barriers require external DC voltage to operate. Most of Ex barriers act as an active component for the AI module side. This means AI module should be passive (4-wire AI module).

I hope it's more clear in the attached file.

Regards,

H-H

H-H

Hello Wago,

I thought it was clear. I hope you wouldn't get more confused by what follows.

Basically, you should understand the possible connections and terms of normal applications where transmitters are connected directly to analog input modules.

Active/source device (module) means that this device has a DC potential across its terminals.

Passive/Sink means this device doesn't generate any voltage across its terminals.

Two wire transmitter is a passive component (varies the mA in the loop according to measurement  but needs DC voltage to operate).

Two wire analog input module is an active module (has DC voltage across its terminals to supply 2-wire transmitters).

4-wire transmitter means it has separate two wires for power and and two wires for signals. The 4-wire transmitters will have (most likely) active 4-20mA.

You can't have two active components in a single side of the loop.

A two wire transmitter (passive) requires an active analog input module (2-wire analog input module).

A 4-wire transmitter (active) requires a passive analog input module (4-wire analog input module).

The barrier is a device that is used for transmitters in hazardous area (Ex barrier) or for higher isolation voltage (Isolator) between field and DCS/PLC.

The barrier acts like an analog input module for the transmitter and acts like a transmitter for the PLC.

Most of Ex barriers require external DC voltage to operate. Most of Ex barriers act as an active component for the AI module side. This means AI module should be passive (4-wire AI module).

I hope it's more clear in the attached file.

Regards,

H-H

 Mr.H-H

  best explain, thanks.

But as you explained,  barrier is compulsory if both are same.

Am I right?