Reference
MVI56-HART ♦ ControlLogix Platform
User Manual
HART Multi-drop Master Communication Module
Page 96 of 171
ProSoft Technology, Inc.
October 13, 2011
If the module is configured for multi-drop auto-polling (Auto-Poll Code = M), the following
diagram applies:
In multi-drop mode, the channel will poll for instruments 1 to the value set in the MAX
DEVICE COUNT parameter. For each device found, it will continuously poll for data using
command 3. After a certain number of iterations, the HART Driver will ready the
configuration data for the next device (if there is one). Each time configuration information
is acquired, it will be for a different slave device if more than 1 slave is recognized by the
channel. Less frequently, the channel will poll for devices not found in the original search
of the network using HART command 0. If communications is lost with all devices, the
module will try to establish communications with the devices using command 0. If user
commands are present and enabled, they will be executed after the data polling of the
devices.
Multi-drop Mode Example:
The intent is to show when using Multi-drop mode how the Auto-Poll DB Address and
Max Device Count parameters should be used.
If the configuration file sets the following parameters:
Parameter
Value
Config File Section
DB Address Status
3660
[HART PORT 0]
Auto-Poll DB Address
400
Max Device Count
15
