DL8000 Preset Instruction Manual
B-4
Modbus Communications
Revised February-2016
Field
Description
Slave Mode
This
display-only
field shows the error code for the
last received Modbus message. This field is
applicable only in slave mode. Valid values are:
0
No Error.
1
Illegal function.
2
Illegal data address.
3
Illegal data value.
Event Logging
Enables the DL8000 to log all parameter changes
made through Modbus in the Event log. Valid values
are
Enabled
(log all events) or
Disabled
(allow
events to be changed but
do not
log those events).
The default is
Enabled
.
Start Polling
Starts the Modbus Master polling sequence. Polling
begins with the Starting Request entry on the
Modbus Master Table and proceeds through the
entries in the table. The system resets this check box
when the polling sequence completes.
Note
: You must have previously defined Modbus
Master as the port owner (select
ROC
>
Comm
Ports
>
General
tab).
Starting Request
Defines the starting number (entry) on the Modbus
Master Table from which polling begins.
Number of
Requests
Indicates the total number of requests in this polling
sequence.
Timeout
Indicates, in seconds, the actual amount of time the
DL8000 waits to receive a value message after it
sends a request to the device.
Note
:
Do not enter zero (0) in this field.
Retries
Controls the number of times (
in addition to
the
initial attempt) the Master DL8000 tries to establish
communications with the specified device before
reporting a timeout error. Valid values are between
0
and
25
. The default is
2
.
Note
: Use the Timeout field to adjust the amount of
time between retries.
Continuous
Polling
Indicates whether the system executes the polling
sequence continually. Valid values are
Enabled
(the
polling sequence executes continually) or
Disabled
(the polling sequence executes only on command).
The default is
Disabled
.
Request Delay
Sets, in seconds, a delay between polling request
sequences.
Note
: This field is valid
only
if you
enable
Continuous Polling.