Installation Instructions Manual

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.
Procedure to Restore Burst Mode
If the isol
ated 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 iso
lated barrier does not detect any other HART masters, the isolated barrier
attempts to activate burst mode.

As soon as the isolated barrier receives a burs
t 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 tim
eout time has been exceeded in the absence of communication, all
outputs switch to the defined safe state. Timeout can be adjusted.
Bul. 937C HART Loop Converter Installation Instructions
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