Reading HART data without PDM

Hello;

You need PDM as a HART primary master to set the secondary variables for the HART sensors( maximum 4 variables per HART channel, maximum 8 variables per HART module), to commission the HART modules, to assign parameters to the HART field devices...

Without PDM, you will be able to read the primary variable of each HART device connected to the HART module (if you have inserted the device's EDD file in the module parameters).

As a stopgap recourse, in case of loss of the PDM computer for example, Siemens suggests you use a HART handheld communicator to replace PDM. I have had no chance to test this, but it appears that you could use the handheld to set the device parameters directly.

For more and better information, look at the HART module manual:

SIMATIC ET 200M distributed I/O device HART analog modules

https://support.industry.siemens.com/cs/ww/en/view/22063748

Hope this helps,

Daniel Chartier

I'm not sure about it, but it has to be possible.

If you have HART compatible AI module, you can read/write your sensor using RDREC/WRREC with the right adresses and variables.

Daltone_UK

Is it possible to read HART data from a device without having PDM installed if you have HART AI cards?

Yes, you can, each AI module has data records of which two per channel can be used to write HART requests and read HART responses

It's not trivial though, the request is a byte string that must be composed

The returned data must be unpacked and as an example, HART sends characters as 6 bit items in an array of bytes, so you must unpack even string characters etc.

Theoretically you can read and even write any instrument (device) parameter, but since everything except the universal HART commands are specific to the device its parameters, you may want to stick to the universal commands. Those do give you some good information though

As mentioned before you use WRREC and RDREC system functions and must write a state engine around those because the communication is asynchronuous

With RDREC you can sniff the data records and see what PDM is sending and receiving

Important note, the data records are one client only, so while you read and write, PDM cannot and vice versa