MVI71-HART ♦ PLC Platform
Reference
HART Multi-drop Master Communication Module
User Manual
Page 79 of 146
ProSoft Technology, Inc.
Multi-drop Mode
Important:
If the HART device address is between 1 and 15, you must configure the
channel for multi-drop mode.
If the unit is set for multi-drop mode, the module will poll each unit attached to the
channel starting with polling address 1. The parameter MAX DEVICE COUNT in the
configuration determines the maximum slave address number to be polled in multi-drop
mode. For example, if the MAX DEVICE COUNT parameter is set to 3, the channel will
poll for polling addresses 1, 2, and 3. It is important when assigning the device polling
addresses for instruments on a channel to start with 1 and successfully increase the
value by one until the last instrument is assigned an address. If you set the MAX
DEVICE COUNT parameter to 2, and assign the two instruments addresses 1 and 15,
the polling address 15 will never be used (only addresses 1 and 2). Therefore, the
second instrument will never be polled and will be in communication failure. Up to 15
instruments can be assigned to a single channel (polling address 1 to 15).
