MBS Protocol PLX3x Series
User Manual Ethernet and Serial Gateways
Page 136 of 218 ProSoft Technology, Inc.
May 26, 2016
Master Port: Modbus Slave List Status
Slave List Status values for each Master port are returned to the address
locations specified in the following table.
*Status data for Ports 2 through 4 is only present in 4-port MBS gateways.
Port 1 Slave List Status Layout
The addresses listed are for Port 1 only; but the format is the same for each port.
The start address for each port is given in the previous section.
Internal
Database
Address
(Example)
The slave status list contains the current poll status of each slave device on a
Master port. Slaves attached to a Master port can have one of three states.
The slave has not defined in the command list for the Master port and will not be polled
from the Command List.
The slave is configured to be polled by the Master port and the most recent
communication attempt was successful.
The Master port has failed to communicate with the slave device. Communication with
the slave is suspended for a user defined period based on the scanning of the
command list.
Slaves are defined to the system when the gateway loads the Master Command
List during start-up and initialization. Each slave defined will be set to a state
value of 1 in this initial step. If the Master port fails to communicate with a slave
device (timeout expired on a command, retries failed), the Master will set the
state of the slave to a value of 2 in this status table. This suspends
communication with the slave device for a user-specified Error Delay Count.