Hi..I`m new to this process automation field. I searched for both of these things on the internet but cudn`t find anything.. MUX I know lets u select 1 signal out of the N input signal..But HART pass thru..no idea about it..

Hope to find an ans here..

Cheers
Tashar

 

HART Multidrop network might be termed 'mux'
http://www.hartcomm2.org/hart_protocol/applications/understanding_hart/multidrp.html

HART pass through:
see page 2 of this document for HART pass through
http://www.hartcomm2.org/download/fldev.pdf

MTL uses it this way:
"HART Pass Through:
Several digital HART pass through variables are also available for use in your control system, enabling you to monitor more than the HART device's process variable. HART integration provides you with a process-ready control system."

HART devices typically have multiple variables (body temperature of a pressure transmitter)which are accessible via HART.

Carl

 

HART is a two-way interface to "smart" analog devices. Pass-thru simply means that particular entity passes the HART information on to some other entity. Here are some of the data HART can exchange.

Device Configuration or re-configuration
Device Diagnostics
Device Troubleshooting
Reading the values of additional measurements provided by the device
Device Health and Status

The HART communication foundation web site provides more information.

HART pass thru..no idea about it..
Hope to find an ans here..
Cheers
Tashar

 

Thanx Carl & some_guy for your valuable inputs..

From a little more research I got to know that HART pass through(I/Os)& MUX are basically used to filter out the digital data superimposed on to the analog data.Then this Analog data(i.e. the transmitter readings etc) is sent to the DCS & the stripped Digital data(i.e. info like device health) is sent to the Instrument Asset Management System(IAMS).

So,does HART pass through I/Os & MUX are used only for separating the two signals ie analog & digital & then sent to the DCS & IAMS resp, or they `ve some other appl as well??

 

Hi, Devices with "Hart Pass-Thru" capability simply means that the HART(digital) signal superimposed on the 4-20mA signal will not be blocked by the device and will therefore allow the Hart data to be read on the "control" side of that device to allow for diagnostics, configuration etc to be done from the "control" side. If it does not have Hart pass thru, you will only be able to communicate to that device on the "field" side of that device for your Hart.

Hope that helps....

 

Multiplexer: connects to multiple HART devices (in parallel with DCS or PLC)and digitally "scans" (communicates with) one by one and pass the data up to some software over a faster network such as Modbus or PROFIBUS or RS485

Pass-through: instead of using a stand-alone multiplexer, the HART communication is built into the DCS or PLC AI/AO card enabling the device data to "pass-through" (the DCS/PLC) up to some software over the DCS/PLC control-network.

For this and other stuff you did not know about HART take a look at the yellow book "Fieldbuses for Process Control: Engineering, Operation, and Maintenance" buy online:
http://www.isa.org/fieldbuses

Cheers,
Jonas