MBS Protocol
PLX30 Series
User Manual
Ethernet and Serial Gateways
Page 128 of 200
ProSoft Technology, Inc.
September 19, 2012
Parameter
Value
Description
RTS On
0
to
65535
Specifies the number of milliseconds to delay data transmission
after
Ready To Send
(RTS) is asserted.
RTS Off
0
to
65535
Specifies the number of milliseconds to delay after the last byte of
data is sent before the RTS modem signal is set low.
Use CTS
Line
YES OR NO
This parameter specifies if the
Clear To Send
(CTS) modem control
line is to be used or not. If the parameter is set to
NO
, the CTS line
will not be monitored. If the parameter is set to
YES
, the CTS line
will be monitored and must be high before the gateway will send
data. Normally, this parameter is required when half-duplex
modems are used for communication (2-wire). This procedure is
commonly referred to as hardware handshaking.
Master Configuration Parameters
Parameter
Value
Description
Response
Timeout
0
to
65535
Specifies the command response timeout period in 1 millisecond
increments. This is the time that a port configured as a Master will
wait for a response from the addressed slave before re-transmitting
the command (Retries) or skipping to the next command in the
Command List. The value to specify depends on the communication
network used and the expected response time (plus or minus) of the
slowest device on the network.
Retry Count
0 to 10
Specifies the number of times a command will be retried if it fails.
End of
Message
Delay
0 to 65535
Specifies a time delay in milliseconds to be added to the 3.5
character time delay used by the module to recognize the end of a
message. Certain applications may require validation of Modbus
messages with more than 3.5 character time between consecutive
bytes (example: modem applications). A value of 0 will cause the
default end of message delay to be used.
Minimum
Command
Delay
0 to 32767
Specifies the number of milliseconds to wait between receiving the
end of a slave's response to the most recently transmitted command
and the issuance of the next command. This parameter can be used
to place a delay after each command to avoid sending commands
on the network faster than the slaves can be ready to receive them.
This parameter does not affect retries of a command, as retries will
be issued when a command failure is recognized.
Error Delay
Counter
0 to 60000
Specifies the number of poll attempts to be skipped before trying to
re-establish communications with a slave that has failed to respond
to a command within the time limit set by the
Response Timeout
parameter. After the slave fails to respond, the master will skip
sending commands that should have been sent to the slave until the
number of skipped commands matches the value entered in this
parameter. This creates a sort of
slow poll
mode for slaves that are
experiencing communication problems.
Command
Control Reg
-1
0 to 3900
This parameter allows the execution of commands in the Command
List (page 131) to be controlled by setting a value of zero (0), one
(1), two (2), or three (3) into a 100-register area of the gateway
database, beginning at the address entered in this parameter. If
commands in the list are specified with an Enable code of zero for
