Measurement unit conversion, without plc

JPINE · Apr 11, 2012

I am currently trying to convert a customer's panel view from standard to metric units of measure. The problem is, I have no way to touch the PLC as it is off the coast of Brazil. I am currently using numeric displays and numeric inputs. I need to be able to write to the PLC in standard but display and interface in metric.

Is this possible? Can tag expressions write to a PLC after an arithmetic function?

jstolaruk · Apr 11, 2012

PV? or PV+?

In PV+, you can create new tags in the HMI to apply scalars and offsetts to analog values read from the PLC - whammy, you got metric for display.

I can't remember in PV but I'm pretty sure you can also.

TConnolly · Apr 11, 2012

I know this doesn't help your current situation, but the sooner the US decides to quit acting like a third world country and join the rest of the world in using the SI system the sooner these kinds of problems will go away for good. We operate factories in the US and Europe so we usually dimension product in mm. But we still dimension our tooling in inches.

.

IMO two simple changes would accelerate the adoption of the SI system. 1)Sell gasoline by the liter - we already sell soft drinks that way so its not a big deal, everyone knows how big a liter is. 2)Report the weather in °C.

seppoalanen · Apr 11, 2012

Do You use horse power in US if You heating something? Your motors works with them.
They are using inches and foot in US, Liberia and Burma. Other 7 billion people use metric, SI / decimal system.
Why, maybe there are some kind of protectionism in the other world.

bce123 · Apr 11, 2012

Do You use horse power in US if You heating something? Your motors works with them.
They are using inches and foot in US, Liberia and Burma. Other 7 billion people use metric, SI / decimal system.
Why, maybe there are some kind of protectionism in the other world.

I use a microwave but if i had a meter wave it would make quick work on some footlong dogs

JPINE · Apr 12, 2012

jstolaruk said:
PV? or PV+?

In PV+, you can create new tags in the HMI to apply scalars and offsetts to analog values read from the PLC - whammy, you got metric for display.

I can't remember in PV but I'm pretty sure you can also.

It is a PV+. I was able to read in metric via the tag expression, but I also need to write in metric without touching the PLC, as it is out of reach. I'll work with the new tags to see what I get. I am writing to integer files in all cases so far. I also did not create the program, the PV+ showed up in UPS.

Also, I completely agree. I love that America is unique, but let's be unique some other way. Metric makes sense.

jstolaruk · Apr 12, 2012

JPINE said:
......but I also need to write in metric without touching the PLC.

Agreed, that might be a little tougher, if not impossible, without PLC access.

JPINE · Apr 12, 2012

I don't have much experience with expressions, but I'm pretty sure I wouldn't be able to input a metric value, and have it sent to the PLC scaled for standard.

jstolaruk · Apr 12, 2012

JPINE said:
I don't have much experience with expressions, but I'm pretty sure I wouldn't be able to input a metric value, and have it sent to the PLC scaled for standard.

I'm pretty sure numeric entry can't be scaled :^(

bernie_carlton · Apr 12, 2012

Use 'HMI Tags' for all entries. They provide for scale and offset which works properly in both directions.

We actually set up two sets of HMI Tags, one set scaled for metric and the other left as standard. We created two of each display or entry control. We provided the operator with a toggle switch to select and used the visibility feature to select the proper operators. It was a bit of work but it ended up pretty seamless as far as the operator was concerned.

jstolaruk · Apr 12, 2012

bernie_carlton said:
Use 'HMI Tags' for all entries. They provide for scale and offset which works properly in both directions.

I stand corrected - good information to know if I ever get in this kind of trouble. Thanks Bernie!

Measurement unit conversion, without plc

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