Control.com - Nerds in Control

The Moore FieldPac 348 has been a great little unit for a small hand full of remote applications. While our refinery has a large installed DCS base, we have some remote tank farm operations that begged for reliable stand alone controllers. The 348 was a wash down rated good outdoor unit that also talked HART. Setting up the HART communication for unit specific commands was a challenge, but our Bristol Babcock RTU systems allowed for custom scripts to handle this. Oh wait, now that Bristol 3335 unit is also obsolete.

All options I have found on Internet searches come up with panel mounted replacements that are not so good for outdoor mounting. My preference would be something that talks MODBUS over RS485 as that is our easiest remote access and most versatile. Alternatively, I am hoping someone has suggestions on devices that can allow for custom HART communication over two wire access as well. The Bristol device allowed me to write a fully functional script for unit specific HART commands well outside the global HART commands. Remote SP ramping was easily implemented and has been a great success.

Any help on suggested devices would be greatly appreciated.

If nothing else, if any of you Experts that keep a pulse on manufacturers know that the industry has given up on wide temperature range even wash down rated stand alone single loop controllers, that might allow me to start seeking an alternative solution (like local PLCs with touch screens that can be field mounted).

Honeywell 1/4 DIN UDC controllers are NEMA 4 rated. It isn't clear what you mean by wide temperature range.

I am unaware of any single loop controller that is HART programmable, in part because the generic HART parameters (tag, range, eng units, etc) are field instrument related, not controller rated.

Carl

The temperature operating range we are seeking goes from -10 Deg F to 120 Deg F as we see that range here in the Ohio River valley. The DIN option may work and I will check it out more closely, but operator access to making local adjustments inside a NEMA 4 box typically is a stumbling block.

As for HART, I used the Moore FieldPac 348 with success and it does indeed use HART for both the standard commands (Repeats things like PV and Secondary variables as you configure them) but also has device specific things like Mode changes and SP ramping. The 348 was great in that it had a user friendly faceplate, and was wash down rated for a wide temperature range and could be remotely operated via 2 wire serial (HART in this case).

As I am not set on finding a HART compatible, my focus is more to find a suitable environmentally applicable device. The MODBUS serial communication is actually easier to implement.

I did look up the UDC a little and found the lower temperature limit of 32 Degrees F. Evidently freezing of the LCD or LED displays is the stumbling block. The Moore 348 had a small heater element behind the LCD to get around that issue. If I could only find a replacement.

Thanks for the Honeywell recommendation.

If that unit is otherwise suitable, could you maybe add a 5W resistor or something behind the faceplate? You could do a test to see temp rise above ambient vs. number of watts and that would tell you what wattage resistor you needed. Then you can power the resistor from a thermostat mounted in panel or outdoors, so you aren't adding to the instrument heat load when it's 120 outside.

Note that there could be a difference between a rated "faceplate" (of something which needs to be put into a panel to cover the back terminals) vs. a totally self-contained unit that needs not be put into any panel.

Cheers,
Jonas

I will go with Carl Ellis on this one, the Honeywell UDC is NEMA 4 when mounted in a NEMA 4 enclosure. When specifying, be sure to select the Auto/Manual option code, otherwise you get Auto/Manual buttons that are disabled.

Roy

For clarification: the NEMA 4 rating for the UDC is for the bezel/faceplate being sealed to NEMA 4 standards when used with the factory bezel gasket and the 4 screws that tighten the faceplate to chassis (part of the UDC's NEMA 4 package).

Like any panel mount box, the enclosure has to be NEMA 4, too, like Roy mentioned, because the behind-the-panel parts of a UDC are exposed to the elements.

I suspect that a strip heater wrapped around the UDC case close to the display (I saw an trade journal ad just recently for self-regulating strip heaters, somewhere (?)) would provide sufficient heat to keep a UDC display running well below freezing, but I've never done it, all ours are mounted indoors.

UDC serial Modbus over RS-485 works great. Avoid the ethernet Modbus, it has problems.

Carl

"Avoid the ethernet Modbus, it has problems."

That kind of made me chuckle. I have used some Modbus over TCP/IP but mostly via bridges like the CEV 174 from Siemens. That works very well. I have also seen warnings about MB over TCP/IP like yours so I respect that very much and will likely stick with the RS485 option.

The UDC specs on wash down rating (Given proper bezel installation as you pointed out) probably come closest to what I need. Having to create my own enclosure and heater assembly always has you concerned that you are messing with manufacturer specs and warranties. The Moore 348 was very nice in that it was fully self contained for panel or outdoor mount with no additional equipment required.

I think what I am finding out from everyone's helpful suggestions is what I suspected. Manufacturers don't have a high demand for this kind of application and as such don't supply such a device anymore. Unless someone else knows of a gem that does have the heater/enclosure as part of the assembly, then the UDC option is likely the direction I will have to take.

Obsolescence is a wonderful thing. At one point, necessity as the mother of invention caused Moore to create a fit, but evidently, I work at a place that still uses field applications that no one else does.

Many thanks.

I'm not sure why you are putting a heater in the enclosure. If it's NEMA 4 there should be no moisture. If it's for extreme low temperature, I would use a few inches of self limiting heat trace. Yes, it's a real pity that the Moore is out of production it was a good fit for mining flotation cells. On the last mining job I used the Honeywell with cover screws. Just be careful when you order them that you ask for Auto/Manual firmware if you need it. Mine came without and I had to upgrade later.

Roy

The heater is for extreme low temperatures (at least those we frequently see below 32 Deg F). Most cases it always involves the LCD panel for about any unit going.

A previous suggestion was to install a small 5W heater inside the case near the LCD portion. I am pretty sure that is exactly how Moore made the 348 available in a wider temperature range. I am not sure many manufacturers would stand by their product if you modify it in that manner.

Thanks for the tip on the A/M option for the UDC, I would have regretted not knowing that down the road.