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ABlearner

SMC pressure sensor

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Hi!

Allen bradley PLC RS Logix 5000

I have a problem with a SMC pressure sensor (ISE30A if I remember correctly). When I monitoring the raw data from the ananlog module, I get about -7710 value, when the smc display shows about 0. There are another SMC pressure sensors too, and if the sensors displays shows 0 then the values what I get form the analog module is about 0 too, so the others work properly. But this one don't.  I already check the wiring. I have no clue waths the problem.

Any idea from anybody?

Thank you for your help.

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Can you post a pic of the program? What are you using for a scaling function?

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So I watched the raw data from the another channels. I talking about 1794 IF4I. The first channel is not used. But when I monitoring the values, there is about -7700 value too. I tryd to remove the SMC pressure wire from the anlog module, then monitoring the value, and the value is not changed. But the channel 1 and 3 are operate correctly.

What do you think maybe the module is not good ? Or I need to settings some things ?

Unfortunatelly I'm really beginner. 

JDHammond1 thank you for your letter. Where can I found the scaling funcitons ?

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I observed the raw data from the PLC and maybe I found a clue. The underrange bit is 1 (set), wich means the signal is too low. In this case what do you think gus whats the problem ? Maybe the sensor cause the problem? 

Thank you for your any help.

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Do you have the channels configured correctly? IOW, if it's a +/-10V sensor, is that the range set in the module configuration? If it's set for 4-20mA and there is an open in the circuit, you will get the under-range bit and your raw values will be weird. Make sure your sensor is wired to the module correctly.

There's a tech note for the 1794-IE12 and 1794-IE8XOE4 configured for mA signals that may or may not apply to your case (access level: TechConnect):

https://rockwellautomation.custhelp.com/app/answers/detail/a_id/40829

In a nutshell, there's a protective circuit built in to the modules that disables that channel under certain circumstances. One remedy is to make sure the Flex chassis is powered up and operating before the field devices start trying to drive current and to make sure the circuit isn't interrupted while the Flex chassis is powered on.

 

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