Identification Letters for a multiple function device (MV) transmitter 1

[mbellow]

I’ve yet to see a logical multiple function device (MV) transmitter identification written anywhere. I propose the following for transmitters NOT doing flow calculations:

UT-xxxx for a MV utilizing HART communications.
UIT-xxxx for a MVT utilizing HART communications with a LCD readout.
UTN-xxxx or UTX-xxxx for a MV utilizing MODBUS or Fieldbus communications.
UITN-xxxx or UITX-xxxx for a MV utilizing MODBUS or Fieldbus communications with a LCD readout.

I have seen someone try to use ‘FPTT-xxxx’, but I do not think that is correct…

If the MV is also doing flow calculations, I propose UQITN or UQITX as examples.

I would appreciate your learned opinions.

Mike

 

[JLSeagull]

If the multivariable transmitter is a gas flow transmitter with pressure and temperature consider tagging as a flow transmitter and add Mass or a note reference outside the bubble. Perhaps the LCD can display all variables. I would reserve the Q for totalization (quantity). Try to limit the alpha prefix to three characters.

Consider notes to address the Foundation Fieldbus or other multivariable digital communication issue. You could use the bubbles touching for each measurement first alpha with one signal line. If seriously interested, this is likely an area where you should become active in the ISA 5.3 committee. Plan to spend some time communicationg between committee members with the results coming after seven years.

 

[mbellow]

JL, I appreciate the feedback; good comments. If it does do internal flow totalization then I agree with you on the quantity use and Q could, and probably should be used.

Simpler is better, but with a complex device, the alpha prefix almost needs to be 4 characters to try and convey the complexity.

I'll take your advice and try and put a post in one of the other forums. I'll also look into the committe. Thank You!

 

[xnuke]

Companies often adapt ISA-5.1-1984(1992) tagging to suit their purposes, but I prefer to stick fairly closely to it so that anyone familiar with the standard can read my drawings without having to refer to a legend sheet to understand the modifications.

The standard shows groups of four letters for tagging, especially in Table 2. I would not go beyond four, however. Bubbles with tags that are too long can limit the amount I can show on a drawing.

I'd agree that FPTT is a poor tag example. I would tag it UT and use a note or a label external to the bubble per the standard.

Finally, I don't to care to denote what communication method is used. I would tag multivariable transmitters UT or UIT if in indicator is integral to the device and use a note or external label. Per the standard, I try to use the U variable sparingly. If necessary to indicate communications type, add a label next to the data link signal line coming from the device (e.g., H for HART, FF for Foundation Fieldbus, etc.) and indicate what those labels mean in a legend somewhere. I don't know that it adds anything to a P&ID to indicate the communication type, however I might put it on a loop drawing. Out of curiosity, why do you think the signal type needs to be shown?

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[mbellow]

Ok; Ok. Good discussion! Now, if we can get everyone else on board with 'UT' or 'UIT'...

I agree with the label next to the data link cable. I guess by my wanting the signal type in the tag name has more to do with my frustration over people not understanding the instruments. No, the signal type probably should not be in the tag. I appreciate your comments.

 

[controlnovice]

Even if the device is mutlt function, I would use two instrument bubbles joined together to represent one device with two (or more) outputs.

______________________________________________________________________________
This is normally the space where people post something insightful.

 

[mbellow]

Yes, I agree. The touching instrument bubbles for each function would still be needed.

 

[mbellow]

ANSI/ISA-5.1-2009 clears it up.
For a multivariable scan device it would be:
UJ-xxxx
UJI-xxxx.

For a single variable 'smart' scanned device it would be:
TJ-xxxx
TJI-xxxx
IF the same single variable 'smart' device used the 4-20mA signal to transmit the variable it would be the normal:
TT-xxxx
TIT-xxxx

THANK YOU ISA!!!