200 Diagnostics
WAGO-I/O-SYSTEM
750
750-880, 750-880/025-000 ETHERNET Programmable Fieldbus Controller
Manual
Version 1.0.1
Pos: 88.23 /Serie 750 (WAGO-I/O-SYSTEM)/Diagnose/Feldbuskoppler/-controller/Fehlerverhalten, Feldbusausfall (750-830, -841, -849, -352,...) @ 6\mod_1259570148859_21.doc @ 46112 @ 23 @ 1
11.2
Fault Behavior
11.2.1 Loss of Fieldbus
A fieldbus and, hence, a link failure is recognized when the set reaction time for
the watchdog expires without initiation by the higher-order control system. This
may occur, for example, when the Master is switched off, or when there is a
disruption in the bus cable. An error at the Master can also result in a fieldbus
failure. No connection via ETHERNET.
The MODBUS watchdog monitors the ongoing MODBUS communication via
MODBUS protocol. A fieldbus failure is signaled by the red "I/O" LED lighting
up, provided the MODBUS watchdog has been configured and activated.
Fieldbus monitoring independently of a certain protocol is possible using the
function block 'FBUS_ERROR_INFORMATION' in the library "Mod_com.lib".
This checks the physical connection between modules and the controller and
assumes evaluation of the watchdog register in the control system program. The
I/O bus remains operational and the process images are retained. The control
system program can also be processed independently.
FBUS_ERROR_INFORMATION
FBUS_ERROR
ERROR
Figure 79: Function block for determining loss of fieldbus, independently of protocol
'FBUS_ERROR' (BOOL)
= FALSE
= no fault
= TRUE
= loss of field bus
'ERROR' (WORD)
= 0
= no fault
=
1
=
loss
of
field
bus
The node can be put into a safe status in the event of a fieldbus failure with the aid
of these function block outputs and an appropriately programmed control system
program.
