Requirements
As of the following product statuses/ STEP 7 hardware update, the HART electronic modules
support the HART fast mode:
HART electronic modules Product version STEP 7 hardware update (HSP)
4 AI I 2WIRE HART 9 053 as of V3.0
4 AI I 4WIRE HART 8
4 AO I HART 9 057 as of V3.0
HART Fast Mode
If a HART command with set SHC bit is recognized by the electronic module for a channel, the
complete HART command processing on the electronic module is reserved for this channel for
approx. 2 s. No other HART command processing is performed during this time on any other
channels of the electronic module.
With each additional HART command with set SHC bit, the electronic module reserves the HART
command processing for this channel again for a further 2 s. If a HART command without SHC
bit set is detected for this channel or if no other command for this channel occurs within 2 s after
the previous HART command, the electronic module returns to "normal" HART command
processing. Result: All HART channels are processed again.
Note
• During the time a HART channel of the electronic module is processing a SHC sequence,
which means that full HART processing capacity of the electronic module is reserved for this
channel, the HART variables of all HART channels are no longer updated. Their values and
quality codes remain unchanged.
• HART requests for other channels are not processed and they are acknowledged accordingly.
• If a HART channel is handled by several clients (e.g. SIMATIC PDM, user program), the
response made available by the module cannot then be allocated to one client with certainty.
HART electronic modules do not support client management.
As of V6.0 SP5, PDM supports the processing of HART jobs with SHC string. To do this, you must
also enable "HART RIO SHC mode" in the "Communication" tab under "Options > Settings" in PDM.
14.10.7 IEEE tags
Properties
For each analog module with HART, you can read in up to 4 IEEE variables in addition to the
analog value. These variables are shown in IEEE754 format. This is the 󹪞oat format according
to IEEEStandard 754 Short Real Number (󹪞oating point format).
Each IEEE variable is accompanied by a status byte. The status byte provides information on the
validity of the measured value.
Analog electronic modules
14.10 Basics of HART
ET 200iSP
396 Operating Instructions, 11/2022, A5E00247483-AK
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