ProSoft Technology MVI69-HART - Manual (Page 102)

Reference MVI69-HART ♦ CompactLogix Platform
User Manual HART Multi-drop Master Communication Module
Page 102 of 169 ProSoft Technology, Inc.
March 29, 2012
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).