I'm wondering if there's a configurable Hart device that will accept two 4-20ma (non-Hart) signals and then output a single 4-20ma signal that represents one of the two input signals, and the second input signal is the Hart signal that is included with the single 4-20ma output. This may seem like a strange request, but the Hart device I'm interfacing with does not support Hart but not Hart multidrop. Hence, I'm trying to find a method to get two 4-20ma signals into a single Hart I/O channel; one becoming 4-20 and the other a Hart channel on that 4-20.

 

I suspect that the market is limited for such a repeater because devices that can read HART signals typcially will have multiple analog input capability to start with - DCS, PLC - and things like recorders don't read HART at all.

If you need a HART AI card for an AB box, I saw Spectrum has a line:
http://www.spectrumcontrols.com/HARTIO.htm

David

 

Thanks for the reply. The problem is with the existing analog I/O card for a Rosemount RS3 system, which is Hart compatible but lacks the Hart multidrop functionality.

 

Bill, this is a strange application but the question I have is, which item does not support mulit-drop? Is it a device or the I/O? If it is the device, it may be noncompliant and you should contact the HART Communication Foundation http://www.hartcomm.org to discuss the issue.

Ed
ed. ladd @ hartcomm. org