RAW and ENG Input Values for Pressure Transducer

[Zog626]

Hello,

Need to confirm this here.

I have a pressure transducer with range -10 to 50 psi, 4 - 20 mA

Is the following correct to input for the RAW and ENG values for the object member?

Raw min. = 819

Raw max. = 4095

Eng min = -10

Eng max = 50

I'm looking at the imported values and see that the previous person who setup the transducers used Raw min. = 0 and I think it should be 819.

Thanks in advance. 

Message Edited by Zog626 on 09-19-2008 12:23 PM

[Rkdomer]

The raw value depends on the PLC and how the analog input module is configured.  The high end of 4095 (20 mA) is what most of our older Modicon Compacts use.  And yes, at 4 mA the raw value would be 819.  The formula to use is: EngMin = (EngMax * LowmA) / HighmA

[Zog626]

So according to the formula, I should be entering 10 for the Eng Min. and 50 for the Eng Max?

Even though the transducer eng range is -10 to 50 psi?

[Rkdomer]

My bad, EngMin & EngMax should be RawMin & RawMax.  Sorry!

[Mike@DTSI]

Lookout has the ability to Scale in the data member config. 

RawMin=819

RawMax=4095

EngMin=-10

EngMax=50

12bit scale.  Set the module for 4-20ma vs 0-20ma and the precision could go up, just beware of a negative (below 4ma) value

Mike

[Zog626]

By module meaning the PLC?  We're using a DirectLogic DL06.

But the Raw and Eng values should still be:

Raw min. = 819

Raw max. = 4095

Eng min = -10

Eng max = 50

Yes?

[jbesselm]

If you ar using an F0-04AD1 module there is a jumper J3 that select either 0-20mA or 4-20mA. The default position is 4-20mA. In the 4-20mA position the pressure transducer range will correspond to 0-4095. If you use the 0-20mA position the transducer range will correspond to 819-4095. Also keep in mind that the module can be configured for the numerical value to be either binary or BCD. This is determined by the modules setup rung or iBox instruction.

Jim

[Mike@DTSI]

Jim got you the answer.  Advantage to the 0-20ma is that you can detect a disconnected signal.  But you could always use the SP relay in the 06. 

Mike

[Zog626]

Things are starting to come together for me here thanks to all your replies. I'm trying to piece together how all this stuff works.

[Zog626]

Okay...the module is set for 0 to 20 mA.

The pressure transducer should be set for 819 to 4095 RAW  Units and -10 psi to 50 psi ENG Units in Lookout.  Yes?