Lots of people like the pushbuttons on industrial pressure transmitters because the basic settings that every transmitter needs can be set up without a HART communicator. This includes things like the tag name, engineering units, LRV (Lower Range Value, the zero, or what 4.0mA represents), URV (Upper Range Value, the span, or what 20.0mA represents) and damping (an average or filter factor that dampens noise).
On the new Honeywell ST700/ST800 series smart transmitters, the tag name and engineering units are easy to configure and self explanatory, but I seem to stumble when setting up the LRV and URV because I’m faced with a non-descript choice. There’s two sets of options (under Transmitter Setup, not Calibration):
OK, either configures an LRV or a URV value, but which is which? What’s the difference?
The simple answer is this:
The Enter LRV/URV is used you want to enter known zero and span numeric values, for instance, LRV = 0.00 PSIG and URV = 100.0 PSIG.
My memory association is that this is like using a PC keyboard’s Enter key after I type in the values.
On the other hand, the Set LRV/URV is typically used for DP transmitters that are installed for level measurement on tanks.
For a variety of reasons, some people establish the zero and span values by using the actual pressure applied to the transmitter at a zero liquid level and a span liquid level. When the liquid level is down at the bottom, Set LRV provides the zero. Then when the liquid gets up to the top, Set URV provides the span. The zero and span are frequently in 0-100% percent.
I’ve always referred to this method as wet configuration because the liquid is wet and you need liquid to do it.
Wet rhymes with set, so it’s easy for me to remember. Set LRV or Set URV is used for wet configuration with actual applied pressures.
Can someone out there in cyberworld help me out?
The Siemens DSIII has pushbuttons and uses numerical codes, M1 or M5 for the menu displays. (Read more about this in my previous blog post.)
M5 is Enter LRV and M6 is Enter URV.
M2 is Set LRV and M3 is Set URV respectively.
The fan-fold cheat sheet that comes under the screw cover uses the word set for the M2/M3 wet configuration. M5 and M6 are described as adjust without pressure (the equivalent of Enter LRV/URV).
But nine times out of 10 the sheet is missing and I’m stuck trying to figure out which is which.
Anyone out there got a memory trick for how to remember the Mx modes on a Siemens DSIII?