Onicon F-4600 Series, Installation And Operation Manual

Page: 33 / 37

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F-4600 With LCD Flow Meter Manual 06/18 - 2020-3 / 35874 Page 33
7.2 DIAGNOSTIC FUNCTION CODE
The MODBUS implementation of the F-4600 supports the use of function code 08, Diagnostic.
When using function code 08, you must also specify the “sub-function” code when sending the message to
the F-4600.
The following sub-functions are supported by the F-4600:
Sub-function Code
Name
Hex Decimal
00 00 Return Query Data
01 01 Restart Communications Option
04 04 Force Listen Only Mode
0B 11 Return Bus Message Count*
0C 12 Return Bus Communication Error Count*
0D 13 Return Bus Exception Error Count*
0E 14 Return Server Message Count
1
0F 15 Return Server No Response Count
1
11 17 Return Server Busy Count
1
12 18 Return Bus Character Overrun Count
1
* Count available in F-4600 diagnostic menu page 1.
1 Count available in F-4600 diagnostic menu page 2.
Description of Sub-functions:
00 Return Query Data
The data passed to the F-4600 in the request data field is to be returned (looped back) in the response.
The entire response message should be identical to the request.
01 Restart Communications Option
The F-4600 serial line port will be initialized and restarted, and all of its communications event
counters are cleared. If the port is currently in Listen Only Mode, no response is returned. This
function is the only one that brings the port out of Listen Only Mode. If the port is not currently in
Listen Only Mode, a normal response is returned. This occurs before the restart is executed.
04 Force Listen Only Mode
Forces the F-4600 to its Listen Only Mode for MODBUS communications. This isolates it from the
other devices on the network, allowing them to continue communicating without interruption from
the addressed F-4600. No response is returned. When the remote device enters its Listen Only Mode,
all active communication controls are turned off. The Ready watchdog timer is allowed to expire,
locking the controls off. While the device is in this mode, any MODBUS messages addressed to it or
broadcast are monitored, but no actions will be taken and no responses will be sent.
The only function that will be processed after the mode is entered will be the Restart Communications
Option function (function code 8, sub-function 1).