Configure a
Modbus
 Master

The
T8151 Communications Interface
 can act as a
Modbus®
master with the addition of the Processor Interface Adapter T8122 or T8123. On a system without the appropriate Processor Interface Adapter connected, configure the
Modbus
 master and download onto the
Trusted®
system. However, no communications activity occurs upon running the system. For details, see Product Description PD-T812x,
Trusted
 Processor Interface Adapter.
Modbus
 master operates on the
T8151 Communications Interface
. This interface can link to a wide range of external devices using either serial or Ethernet links, supporting the
Modbus
 RTU protocol. Modicon™ Open
Modbus
 TCP is not supported.
The
Modbus
 master configuration is performed in three stages: configure a master, configure the slaves serving that master, then configure the messages carrying data to and from each slave.
Configure these settings for a
Modbus
 master:
  • Configuration settings, communications and status reporting
  • Broadcast modes, broadcasting messages to slaves
  • Statistics data, recording the time taken to complete a master poll
mdb_mrcfg
To configure a
Modbus
 master
  1. In the
    T8151 Communications Interface
    , click
    Configure
    Modbus
     Master
    .
    The
    Modbus
     Master Configuration for Chassis 01, Slot 01
     window appears. For example purposes, this procedure configures communications for the first slot of the first chassis.
  2. Click
    Add Master
    .
    The Master 1
    Modbus
     master appears in the structure window on the left.
  3. (optional) Click
    Change Name
     and then type a name for the master.
  4. On the
    Configuration
    tab, define communications and status reporting for the master.
  5. On the
    Broadcast
    tab, enable
    Broadcast Mode
    , and then define broadcast messages for slaves.
  6. On the
    Statistics
    tab, enable
    Report Statistics
    , and then define report statistics data to the application.
  7. Click
    Validate
    .
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