I am doing analog datalogging to troubleshoot some process in my plant. I only have a problem: some of the transmitters that I use are Smart Honeywell digital instruments and as such are sending a digital 4-20 mA signal to the DCS, and the current has no "process meaning". Here is my question: would someone out there know of a module or product that would convert an "analog" DE signal to a true 4-20 mA signal (voltage would also be fine) that could then be used for data logging?

Thanks,

Benito

 

Benito,
I have never seen one. One option - if there are not too many and you have spares - would be to have your DCS folks configure some analog outputs to re-transmit the DE signals as 4-20, for example out to a local JB.

John Rezabek
ISP Lima LLC

 

Honeywell DE instruments can be configured to send a 4-20 mA signal proportional to the process variable instead of the proprietary DE
signal. You would lose the benefits of the extra DE data that way, of course. In a few difficult cases, I have used a DCS analog output
signal to echo a Honeywell transmitter DE process variable to another system, but that can get expensive.

Judy Lesslie

 

I assume that your device(s) output DE to a Honeywell DCS that takes the DE directly.
Because if you don't have a DCS, you can re-configure the device(s) to talk analog 4-20mA with a handheld communicator, known as the SFC or STS103.

If your devices connect to a DCS that is talking DE AND you still need an analog signal, then Honeywell sells a DIN rail mount module known as the MVA that takes the DE signal and converts it to an analog signal. One model outputs only 1 analog output, another model outputs 4 analog 1-5Vdc outputs. The MVA module needs DC power.

The typical layout is to drive both the MVA and the DCS with the DE signal and then you use the analog output from the MVA wherever you need it.

Note that each output on the 4 ch. MVA is a voltage output, not a 4-20mA current signal, with the attendant limitations of voltage signals in an industrial invironment. I don't know what kind of output the single channel MVA has.

Also, be aware that even 4 ch MVA module only takes one DE signal from a single transmitter. The four channel module does NOT take multiple DE signals from multiple transmitters.

The 4 channle module is designed speciically for the SMV multi-variable transmitter used where a single SMV transmitter's DE signal provides 4 variables: DP, working absolute pressure, temperature, and calculated mass flow.

Bud

 

Thanks for all your input,

Actually, what I am doing right now is to program analog outputs as mirror images to my DE inputs. I have browsed the internet and Honeywell buys DE-analog converters and resells it. You could also buy it directly from Vektroncorp.

http://www.vektroncorp.com/

Benito

 

Thanks for all your input,

Actually, what I am doing right now is to program analog outputs as mirror images to my DE inputs. I have browsed the internet and Honeywell buys DE-analog converters and resells it. You could also buy it directly from Vektroncorp.

http://www.vektroncorp.com/

Benito

Hey Benito, I am trying to do the same thing! I'm trying to bring analog devices onto a Honeywell DE system (I want the analog devices to output DE protocol for the Honeywell DCS).

Did you have any luck doing this/any advice on how I could get this done?

 

I worked with Honeywell instrumentation for a couple decades. Honeywell's earlier generation field instruments could be configured to talk either DE protocol or conventional 4-20mA. Current generation uses either a DE comm module or a HART/4-20mA module.

I don't know what the analog input capabilities are for Honeywell's DCS. It's not clear to me whether a given AI point can be configured for DE or 4-20mA, whether a DE input card can be coverted/configured for analog 4-20mA or not. I suspect not, but I just do not know. It's worth inquiring of the DCS owner as to whether AI's can be configured as either DE or 4-20mA. Given that you're asking about DE converters, I would further suspect that the available inputs are not analog 4-20mA inputs.

DE has always been a proprietary protocol with a limited market so there have not been a ton of 3rd party devices dealing with the DE protocol. As of 4 years ago, the 3rd party module that does the opposite of what you want, converts DE to analog, was still available; it is what is described in the posts above.

But I have never encountered any commercial 4-20mA to DE converter.

The straight forward approach is to install 4-20mA inputs for 4-20mA field instruments.