MBS Protocol
PLX30 Series
User Manual
Ethernet and Serial Gateways
Page 138 of 200
ProSoft Technology, Inc.
September 19, 2012
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.
Modbus Port
Address Range
1
4510 to 4764
2*
4910 to 5164
3*
5310 to 5564
4*
5710 to 5964
*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)
Offset
Description
4510
0
Slave #1 Status
4511
1
Slave #2 Status
4512
2
Slave #3 Status
4513
3
Slave #4 Status
4514
4
Slave #5 Status
.
.
.
.
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.
0
The slave has not defined in the command list for the Master port and will not be polled
from the Command List.
1
The slave is configured to be polled by the Master port and the most recent
communication attempt was successful.
2
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.
