hello,

Currently I’m doing a project with some 0-10V sensors. However I’ve observed that the sensors are influencing each other.

I’ve done some tests to figure out what the problem could be but I’m getting stuck and would appreciate some ideas.

So there are a bunch of 0-10 V sensors. There is one sensor that I’ve used for testing because its giving a value of 4.5 V and the values of the others are much lower. When the sensor is connected the levels of the other inputs also increase.

For the record I’m using a siemens temperature sensor qfm2160 and an  Analog Input Module  6ES7 134-6HD01-0BA1

The simplest test is when I don’t connect any sensors to an input card.  All 4 values are around 0. When 1 connect the sensor that is giving 4.5 v, then that input gives a value of 12859. That makes sense. However the other 3 inputs of that card are giving a value of 380.

The same happens when there are actual sensors connected. This is on a different card.

3 of 4 sensors are connected and give a value of around 90. When y connect the 4^thsensor the values of the other sensors go up to about 120.

Iwas expecting that these inputs would be separated and not influencing each other. At least that is wat I want. Anybody any ideas on what I am doing wrong?

What does the documentation of the card say
about the unused analog channels?

On the S7-1200 there are notes on that topic for the voltage measuring analogs.

Module manual, A5E03572832-AF, dated 06/2020, page 15, figure 3-1, shows how to wire up the analog input for voltage inputs.  You do not show correct wiring for your analog input.

Assuming you have all 4 AI's in use, the wires should be:
U0+ (P1) & U0- (P5) for AI0
U1+ (P2) & U1- (P6) for AI1
U2+ (P3) & U2- (P7) for AI2
U3+ (P4) & U3- (P8) for AI3

The module must be configured for Voltage & 0..10V for each channel (or via template)

Are there any PLC diagnostic buffer errors related to this module, like supply voltage missing? 

FrJan

hello,

Currently I’m doing a project with some 0-10V sensors. However I’ve observed that the sensors are influencing each other.

I’ve done some tests to figure out what the problem could be but I’m getting stuck and would appreciate some ideas.

So there are a bunch of 0-10 V sensors. There is one sensor that I’ve used for testing because its giving a value of 4.5 V and the values of the others are much lower. When the sensor is connected the levels of the other inputs also increase.

For the record I’m using a siemens temperature sensor qfm2160 and an  Analog Input Module  6ES7 134-6HD01-0BA1

The simplest test is when I don’t connect any sensors to an input card.  All 4 values are around 0. When 1 connect the sensor that is giving 4.5 v, then that input gives a value of 12859. That makes sense. However the other 3 inputs of that card are giving a value of 380.

The same happens when there are actual sensors connected. This is on a different card.

3 of 4 sensors are connected and give a value of around 90. When y connect the 4^thsensor the values of the other sensors go up to about 120.

Iwas expecting that these inputs would be separated and not influencing each other. At least that is wat I want. Anybody any ideas on what I am doing wrong?

The module is powered on normally. There are only green lights on the module. The online information doesn’t give me any information to work with.

All channels are set to 0-10V.

When you are saying that I’ve not wired the sensors correctly you mean that I can only use a 4 wire sensor. And I cant use a 3 wire sensor?

0_Einstein

Module manual, A5E03572832-AF, dated 06/2020, page 15, figure 3-1, shows how to wire up the analog input for voltage inputs.  You do not show correct wiring for your analog input.

Assuming you have all 4 AI's in use, the wires should be:
U0+ (P1) & U0- (P5) for AI0
U1+ (P2) & U1- (P6) for AI1
U2+ (P3) & U2- (P7) for AI2
U3+ (P4) & U3- (P8) for AI3

The module must be configured for Voltage & 0..10V for each channel (or via template)

Are there any PLC diagnostic buffer errors related to this module, like supply voltage missing? 

FrJan

hello,

Currently I’m doing a project with some 0-10V sensors. However I’ve observed that the sensors are influencing each other.

I’ve done some tests to figure out what the problem could be but I’m getting stuck and would appreciate some ideas.

So there are a bunch of 0-10 V sensors. There is one sensor that I’ve used for testing because its giving a value of 4.5 V and the values of the others are much lower. When the sensor is connected the levels of the other inputs also increase.

For the record I’m using a siemens temperature sensor qfm2160 and an  Analog Input Module  6ES7 134-6HD01-0BA1

The simplest test is when I don’t connect any sensors to an input card.  All 4 values are around 0. When 1 connect the sensor that is giving 4.5 v, then that input gives a value of 12859. That makes sense. However the other 3 inputs of that card are giving a value of 380.

The same happens when there are actual sensors connected. This is on a different card.

3 of 4 sensors are connected and give a value of around 90. When y connect the 4^thsensor the values of the other sensors go up to about 120.

Iwas expecting that these inputs would be separated and not influencing each other. At least that is wat I want. Anybody any ideas on what I am doing wrong?

 

This page explains that you can connect 3wire sensor as well as2 and4 wire sensor.

https://support.industry.siemens.com/cs/ww/en/view/40913432

I don’t know if we have a ground that we need to connect to the card. Never saw a connection for that.

I can't answer the wiring issue, too many AI modules, too many base units for me to keep track of.

I'll assume you've wired the inputs properly. 

If so, the description,

When 1 connect the sensor that is giving 4.5 v, then that input gives a value of 12859. That makes sense. However the other 3 inputs of that card are giving a value of 380.

is a classic example of common mode voltage affecting a non-isolated, typically a single ended, analog input (AI) card.

Siemens expects an entire site to be equipotential, meaning that an earth ground connection is the same potential everywhere.  In reality, that's frequently not the case.

The 0V connection of a voltage input to an analog input card's (-) terminal eventually gets connected to earth ground in a single ended card and in non-isolated cards.

When the source 0V is at a different potential than the analog input 0V potential, that difference in voltage will drive current (according to Ohm's Law) and that creates a ground loop.  The current will develop a voltage drop across any resistance in the ground circuit, creating an offset in the reading, because that offset appears to be part of the signal voltage.

You can measure common mode voltage with a voltmeter, the voltage between the 0V terminals of the source and the AI.

One approach is to pay a lot more for isolated inputs.  Isolated inputs usually have differential inputs, but differential inputs alone will not cure a common mode problem

SIgnal isolators can cure common mode problems because the ground potential is not passed through the isolator.  But one needs an isolator for each channel.

I'll be waiting to see whether this spins out as a wiring issue or a common mode issue.  Please report back what you find.

Boa Tarde

Estou tendo o mesmo problema, alguem poderia me ajudar, pois esse forum ficou em aberto.

Obrigado.

Hello AutoGen_8149187,

AutoGen_8149187

Good afternoon

I'm having the same problem, could someone help me, as this forum is open.

Thanks.

 Best Regards,

The Helping Hand