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By default, the watchdog is not enabled when you turn the controller on. To
activate it, the first step is to set/verify the desired time-out value of the
Watchdog Time register (0x1000). Second, the function code mask must be
specified in the mask register (0x1001), which defines the function code(s)
that will reset the timer. Finally, the Watchdog-Trigger register (0x1003)
must be changed to a non-zero value to start the timer.
Reading the Minimum Trigger time (Register 0x1004) reveals whether a
watchdog fault occurred. If this time value is 0, a fieldbus failure is assumed.
The timer of watchdog can manually be reset, if it is not timed out, by writing
a value of 0x1 to the Restart Watchdog register (0x1007).
After the watchdog is started, it can be stopped by the user via the Watchdog
Stop register (0x1005) or the Simply Stop Watchdog register (0x1008)
4.2.5.1.2 Watchdog Register:
The watchdog registers can be addressed in the same way as described with
the MODBUS read and write function codes. Specify the respective register
address in place of the reference number.
Register address 0x1000 (MODBUS Address 404097)
Designation
Access
Default
Description
Register address 0x1001 (MODBUS Address 404098)
Designation
Access
Default
Description
WAGO-I/O-SYSTEM 750
ETHERNET TCP/IP
Watchdog time, WS_TIME
read / write
0x0000
This register stores the watchdog timeout value as an unsigned 16 bit value.
The default value is 0. Setting this value will not trigger the watchdog.
However, a non zero value must be stored in this register before the watchdog
can be triggered. The time value is stored in multiples of 100ms (e.g., 0x0009
is .9 seconds) It is not possible to modify this value while the watchdog is
running.
Watchdog function coding mask, function code 1...16, WDFCM_1_161...16
read / write
0x0000
Using this mask, the specific function codes can be configured to reset the
watchdog function. The function code can be selected by writing a '1' to the
(Funtion code-1) +
appropriate bit(s) ( 2
Bit 1001.0 corresponds to function code1,
Bit 1001.1 corresponds to function code2...
A value of 0xFF enables Modbus functions code 1 through 16 to reset the
watchdog. It is not possible to modify this value while the watchdog is
running.
Fieldbus Communication
MODBUS Functions
(Funtion code-1...
2
).
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