Ron_S

FX2N-TC

11 posts in this topic

Hi, I have a job to upgrade a panel I did a long time ago.

 

The panel already has a FX1n plc and 4 standalone temperature controllers.

The plc controls the batching and mixing and the temperature controllers - control the temperature.

They now want different actions at different temperatures and so I have ordered an FX2n-TC add-on for the plc.

My question - can I piggyback the wires from the pt100 themocouples at the temperature controller terminals into the fx2n-tc

or do I have to wire extra wires to the thermocouples and make sure the tc's are the double type.

 

 

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You can't piggyback the wires from the pt100's but you can of course use the double or duel output type ones. Do the standalone temperature controllers also have an output of their own (4-20mA etc)? If so you could simply program the controllers to retransmit the values (OK you would have to replace the module you have just ordered).

Edited by Nightfly

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Cheers Nightfly. I am virtually sure the temp controllers don't have a 4 -20 mA output. (I read the spec online - they are extra plugin modules) and I have a spare FX2n-4AD as well

So I better order some 6 core cable and check the temperature probes are doubles. 

 

I knew it was a long shot :)

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What do you mean by "double type" PT100?

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Just now, Veganic said:

What do you mean by "double type" PT100?

 

It’s basically two temperature detectors (resistors) inside the body of a single probe (often called dual, twin, duplex probes etc). Each detector is completely electrically isolated (so it can be fed into separate control systems).

Example

http://uk.rs-online.com/web/p/platinum-resistance-temperature-sensors/3971416/

 

 

 

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On 10 October 2016 at 3:09 AM, Ron_S said:

Hi, I have a job to upgrade a panel I did a long time ago.

 

The panel already has a FX1n plc and 4 standalone temperature controllers.

The plc controls the batching and mixing and the temperature controllers - control the temperature.

They now want different actions at different temperatures and so I have ordered an FX2n-TC add-on for the plc.

My question - can I piggyback the wires from the pt100 themocouples at the temperature controller terminals into the fx2n-tc

or do I have to wire extra wires to the thermocouples and make sure the tc's are the double type.

 

 

PT 100 and TC or thermocouple are two different items. TC can be piggy backed and As Nightfly points out you can't piggy back RTD (PT100) Some controllers can re-transmit.

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The FX2n-TC -ad unit is not the correct one for RTD's you need the FX2n-4ad, you can connect the probes to this and completely do away with the controllers for control and do it all in the PLC (unless that is you need to use the displays) even then, if you have some form of HMI you could display temperatures on that.

 

Steve

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I might be misreading something, but I think there are some misunderstandings here:

  1. 3-wire PT100 is not the same as dual output PT100. One PT100 sensor can simply be connected using 3 wires (compensated) or 2 wires (a 3 wire sensor can be shorted and then you have a 2 wire sensor)
  2. Regarding the modules:
    1. FX2N-4AD-TC = J or K thermocouple elements (NOT PT100)
    2. FX2N-4AD-PT = PT100
    3. FX2N-4AD = VDC or mA signal

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There are some misunderstandings :) and it is my fault.

I actually ordered the  FX2N-4AD-PT  (not TC) it must be because I was setting some thermocouples up last week and the word stuck in my mind.

The company have plenty of spare double PT100's (nearly wrote thermocouples again) That's - for clarification 6 terminal PT100's

And the reason I asked if they could be piggybacked was the controllers read the resistance of the PT100's

and I tried a test with two multi-meters on the same PT100 terminals and read 112 Ohms on both.

 

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On 10/13/2016 at 10:20 AM, Nightfly said:

 

It’s basically two temperature detectors (resistors) inside the body of a single probe (often called dual, twin, duplex probes etc). Each detector is completely electrically isolated (so it can be fed into separate control systems).

Example

http://uk.rs-online.com/web/p/platinum-resistance-temperature-sensors/3971416/

 

 

 

Thanks for the information.  I've not seen those before.

 

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