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Samba SM35-J analog input wiring/configuration question


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Hello all. This is the first time I am working with a Unitronics PLC and would need some help regarding the wiring and configuration of the on-board analog input.

I have an INOR 2 wire transmiter that will transform a PT1000 temp value to 4-20mA signal that the PLC will read(see attached picture1).
So I set the jumper JP8 and JP9 to B so that analog input #0 is set to Current.  Also configured analog input 0 to 4-20mA in VisiLogic.

So I tried to wire the transmitter like it is drawn in the manual of the Samba PLC (manual page 8). Inor terminal 6 to +24 V DC, Inor terminal 7 to analog input of the Samba PLC (terminal 9).

But I don't get any value from the analog input. Have I missed something in the configuration of the PLC or most likely the wiring is not correct.

Any info would be great. Thank you in advanced.

Cheers Aleix.

Picture1.png

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Hi,

You described the problem well, but did not indicate which Sambs PLC model you have in your hands. I think it's a PLC SM35-J-R20 :)

A common mistake when connecting an analog input is to confuse I9 (descrete input) with the 9 pin (AN0) of the controller connector.

Also you can monitor analog input MI via online mode and see what value present. 

 

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Hello.

Yes forgot the most important part, sorry about that. I am using the PLC SM35-J-R20 as you figured it out.

I did monitor the MI variable that I set up in the hardware configuration but it's always 0...  That is why I am assuming that I didn't wire the transmitter to the PLCcorrectly.

Pin 9 is the correct one for the first analog input, right?

 

Cheers

Aleix

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I don't use Sambas and may have this wrong, but check your NPN & PNP settings.  The manual states "If the digital inputs function as npn, analog option is not available."

Also, carefully check your puck specs.  Ensure everything's on the correct terminals.  Some pucks can be very confusing with what they need to work, compared to another.  I'm also assuming that if it is a programmable puck you've done this correctly.

cheers, Aus

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Hello all. Thanks for the input so far guys.

I checked the INOR output with an amp.meter and the Inor outputs around 8mA at room temp (24°C).  I can't get my head around on how to wire the analog input of the PLC seeing that it only has one input terminal.

Do I connect the 6 terminal from the INOR to the 9 terminal of the PLC with the 24V and then the 24V GND to the 7 terminal of the INOR? 

Cheers.

Aleix

 

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Hi Aleix

When you disconnect the wire from terminal 9 of the PLC and put a meter in series with the input, what reading do you get.

make sure that the polarity of the meter is correct with the negative probe in terminal 9.

Do you get the same 8ma or -8ma or nothing.

If nothing re-check your wiring. If -8ma reverse the wires on 6 and 7 of the INOR.

If it is 8ma re-check the jumper settings and the hardware configuration in the program.

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Hello.

Thanks for the tips @sgull, I will try to wire in series a amper meter to check.

I will make a drawing how I got things wired for better understanding of the situation.

@Flex727I checked the manual an wired as it is drawn.  The manual says that the + from the 2 wire transmiter has to be wired to +24V (in my case INOR terminal 6) and connect the - from the transmitter (in my case INOR terminal 7) to the analog input. This is what I tried first and it didn't show any value on ma MI100 which is defined for the first analog input.

Best regards.

Aleix

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Hello all.

I have managed to make the analog input to work. There was indeed a problem with the wiring.

The correct wiring is +24V to 6 of  the INOR and 7 of  the INOR to the analog input of the PLC.

 

Thanks for the help.

Cheers

A

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