Pepperl+Fuchs KFD2-HLC-Ex1.D Series Manual page 23

HART Loop Converter KFD2-HLC-Ex1.D(.**)
Installation
Polling Mode (command and answer)
The isolated barrier deactivates the burst configuration of the field device. The isolated
barrier performs the field device query using HART command 3. See chapter 3.5.6.
Procedure to Restore Burst Mode
If the isolated barrier does not receive any more data from the field device in burst mode, the
following actions are taken:
• The isolated barrier switches to polling mode.
• The isolated barrier checks whether another HART master has started in the query
signal circuit. If the isolated barrier has detected a HART master, the restoring of burst
mode is interrupted.
• If the isolated barrier does not detect any other HART masters, the isolated barrier
attempts to activate burst mode.
• As soon as the isolated barrier receives a burst message from the field device, the
isolated barrier switches from polling mode to burst mode.
This process enables other HART masters to deactivate burst mode momentarily for service
work.
Time Out (communication loss)
When the timeout time has been exceeded in the absence of communication, all outputs
switch to the defined safe state. Timeout can be adjusted.
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