15
Hauser
HART Loop Converter HMX50
3.3.3 Connecting a HART Handheld to the Field Device
You have two options for connecting a HART handheld to the field device:
• Connection to terminals 22/24 of the isolated barrier, see chapter 3.3.2
• Connection to the field cables from the isolated barrier to the field device
Transmitting the HART signal using the current outputs of the isolated barrier is not
possible.
3.3.4 Description of HART Operations
Dynamic Query of Variables
Universal HART command 3 is used to query dynamic variables from the field device. This
query is done either directly or by activating burst mode.
Burst Mode
Burst mode is the preferred method because this mode guarantees the fastest signal
transmission. The isolated barrier always tries to set the connected field device to burst
mode. See chapter 3.4.6.
The command for burst mode activation is sent to the field device under the following
conditions:
• after a restart or
• after resetting the isolated barrier after restarting the field device. In the process,
communication between the field device and isolated barrier must have been
reestablished again after a time out.
Risk of explosion
Danger of explosion when using a noncertified HART handheld in a hazardous area.
‣
Use a HART handheld certified for use in hazardous areas if the field cables lead into a
hazardous area.
DANGER
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