ad Pressure switch to BRX

[PLCGuy]

I bought a QPSH-AN-42. Pressure switch range of -14.5 to 145psi. Running a BRX analog card BX-08DA-2B. With no load on the sensor I see 3000 on WX0. Is this right? If it is, do I need to scale it to the card resolution? Then scale it again for proper readings? In the end I am trying to use it to measure vac lift. 30mg/h20 is same as 14.5 psi so they say. Just trying this out as an experiment. But them main issue is why the 3000 on WX0 with no load. This is the first time using a analog output 4-20ma from AD. I usually use 0-10vdc versions from another vendor.

[plcnut]

You have 15 bits of resolution, with a rage of -14.5 to 145 psi, so 0 psi will equal approximately 3000 counts. You just need to use a SCALE instruction to convert the raw value to psi measurements. You should be able to enter WXn as the input, In Min 0, In Max 32767, Out Min -14.5, and Out Max 145.0 and the output should contain psi.

[BobO]

You have 15 bits of resolution, with a rage of -14.5 to 145 psi, so 0 psi will equal approximately 3000 counts. You just need to use a SCALE instruction to convert the raw value to psi measurements. You should be able to enter WXn as the input, In Min 0, In Max 32767, Out Min -14.5, and Out Max 145.0 and the output should contain psi.

This ^^.

[Bolt]

Also, you could put the -14.5 and 145 in as parameters to auto scale WXn to RXn in the analog module's setup, and would save yourself a rung of code.

[PLCGuy]

Thanks. that is what I had in there so I thought. I bet I forgot to put the negative in front of the 14.5 cause I just did it again. lol  What I am going to try next is use this sensor to measure vac lift. -14.5 psi equals 30 water lift so they say. I am going to attempt to scale this and see what happens. Vac Lift sensors cost us 450 bucks. Hey if I can do it with a 69 dollar sensor...

[Garyhlucas]

We use the -14.5 to 30 psi transmitters on vacuum and they work fine.

[Controls Guy]

Should work fine, but iirc, 1 psi is about 27"wc and change, so full vacuum is something like 408" so you'll need to scale accordingly.  Probably won't give very good service if you're trying to measure a few inches (too small a percentage of full scale).

[PLCGuy]

Having a hard time scaling. Most our readings are around the 30 to 45 range for our product.