PLC technical inquiry

ihab · Jan 15, 2018

An automation system having a dedicated PLC connected to feedback potentiometer supplied via 0-10V, an added automated system based on another PLC will share same feedback potentiometer with same characteristics and supply as an input for another anlage module of that PLC. I would like to know how could I split the potentiometer input to be able to used as an anlage input of two different PLCs at the same time ?!

strantor · Jan 15, 2018

ihab said:
An automation system having a dedicated PLC connected to feedback potentiometer supplied via 0-10V, an added automated system based on another PLC will share same feedback potentiometer with same characteristics and supply as an input for another anlage module of that PLC. I would like to know how could I split the potentiometer input to be able to used as an anlage input of two different PLCs at the same time ?!

1. make sure the inputs of the 2nd PLC are high enough impedance that they won't pull the signal down.
2. make sure the 2 PLCs do not have a voltage differential between their grounds.
3. Connect the grounds between the two PLCs
4. Now you can simply run a 2nd wire from the pot wiper to the 2nd PLC

cardosocea · Jan 15, 2018

Connect the potmeter through a signal splitter? Phoenix contact has a lot of those utility like devices.

BobB · Jan 15, 2018

Signal splitter for sure - then no issues. Make sure it is an isolated type.

ihab · Jan 15, 2018

cardosocea said:
Connect the potmeter through a signal splitter? Phoenix contact has a lot of those utility like devices.

Thanks for your reply, can you advise exact module ?

ihab · Jan 15, 2018

cardosocea said:
Connect the potmeter through a signal splitter? Phoenix contact has a lot of those utility like devices.

strantor said:
1. make sure the inputs of the 2nd PLC are high enough impedance that they won't pull the signal down.
2. make sure the 2 PLCs do not have a voltage differential between their grounds.
3. Connect the grounds between the two PLCs
4. Now you can simply run a 2nd wire from the pot wiper to the 2nd PLC

thanks for your reply, eventually it may effect the original design. I think splitting this signal is much better and more safer

janner_10 · Jan 15, 2018

If one PLC has a spare Analogue output, use that to mirror the pot input. Saves buying a splitter.

jaden · Jan 15, 2018

While they may be harder to find now, there used to be double ganged pots available. Two separate pots mounted on a common shaft.

cardosocea · Jan 15, 2018

This is one:

https://www.phoenixcontact.com/onli...pcck=P-13-15-01-02&tab=1&selectedCategory=ALL

But the output will be current only.

This one seems to do what you need.

https://files.pepperl-fuchs.com/webcat/navi/productInfo/edb/274349_eng.pdf?v=20180112000158

Mickey · Jan 15, 2018

Another option...

http://www.miinet.com/InterfaceSolutionDownloadCenter/Products.aspx?product=171

RocketTester · Jan 15, 2018

If the 2 PLC's are in the same Control Room, one would normally tie them to the same analog and digital commons (why they are called "common"). In that case, just wire the signal+ to both PLC's and connect signal- to analog common (as post #2 said). To insure each doesn't affect the signal, see if connecting it to each PLC input affects the reading. If the PLC analog inputs are "differential", i.e. separate sig+ & sig- pair for each channel, then even less concerns.

isiah_s · Jan 15, 2018

1. Connect two plcs by ethernet and share date

2. have one date take the analog input and generate an analog output to be the input for the other one.

pot---> AI ---> PLC A ---> AO ---> AI ---> PLC B

3. use a buffer amplifier

BobB · Jan 15, 2018

I use these but not sure if available where you are. https://www.apcs.net.au/products/ds/ds235305.pdf

strantor · Jan 15, 2018

RocketTester said:
If the 2 PLC's are in the same Control Room, one would normally tie them to the same analog and digital commons (why they are called "common"). In that case, just wire the signal+ to both PLC's and connect signal- to analog common (as post #2 said). To insure each doesn't affect the signal, see if connecting it to each PLC input affects the reading. If the PLC analog inputs are "differential", i.e. separate sig+ & sig- pair for each channel, then even less concerns.

Thank you for correcting my terminology and validating the concept I put forward. The nearly unanimous answer of "splitter," had me wondering if I might be guilty of some Mickey Mousery. I've done this several times and never had a problem. And I've seen it done by others too.

ihab said:
thanks for your reply, eventually it may effect the original design. I think splitting this signal is much better and more safer

There are some scenarios where it wouldn't work, but that's why I prescribed the voltage checks. If it won't work, then it won't work, ever. If it will work, and it worked on day#1, I don't expect that it would "eventually" affect the performance. What kind of long-term degradation are you expecting this to cause?

ihab · Jan 15, 2018

Thanks everybody for the precious experiences I got.

PLC technical inquiry

ihab

Member

strantor

Member

cardosocea

Member

BobB

Lifetime Supporting Member

ihab

Member

ihab

Member

janner_10

Lifetime Supporting Member

jaden

Member

cardosocea

Member

Mickey

Lifetime Supporting Member

RocketTester

Member

isiah_s

Member

BobB

Lifetime Supporting Member

strantor

Member

ihab

Member

Similar Topics