Beckhoff EL28 Series Documentation page 37

2.5.5.2 Diagnostics per channel
Open Load (Index 0x60n1:02 [} 42])
The open load detection shows that no load is connected when the output is switched on.
The "open load" bit (index 0x60n1:02) is set to TRUE if the output is TRUE and the output current is less
than typ. 0.2 mA.
Short Circuit to 24V (Index 0x60n1:04 [} 42])
A short circuit to 24 V is detected if the output is FALSE, but nevertheless a voltage of more than typ. 10 V is
present. The "Short Circuit to 24V" bit (index 0x60n1:04) is set to TRUE. The corresponding LED flashes red.
Overtemperature (index: 0x60n1:01 [} 42]) – overcurrent (index:0x60n1:03 [} 42])
The "Overcurrent" bit (index: 0x60n1:03) is set in case of an overload. The LED lights up red. The channel
heats up, so that the "Overtemperature" bit (index: 0x60n1:01) is set on reaching an upper limit temperature
(see fig. Overload current limitation [} 33]).
In the case of a short-circuit the channel overheats very quickly, leading to it being switched off. Once the
temperature has cooled down to below a lower limit value following the switch-off, the output is switched on
again. The temperature, however, is then still so high that the "Overtemperature" bit (index: 0x60n1:01)
remains set. Thus the LED remains red as long as the short-circuit is present.
Overcurrent diagnostics is no longer possible once the output is switched off. The "Overcurrent" bit (index:
0x60n1:03) is only set to TRUE when the output is switched on again (see fig. Schematic illustration of the
thermal switch-off in case of overload [} 33]).
2.5.5.3 Device diagnostics
General error (index 0xF600:11 [} 42])
If the "Common Fault" bit (index 0xF600:11) is set, there is an error on one or more channels.
It is thus possible in the "Compact Diagnostics" process mode to determine that errors have occurred on one
or more channels.
Device overtemperature (index 0xF600:12 [} 42])
The device temperature rises due to an overload, a short-circuit or excessively high ambient temperature. If
the device temperature exceeds the upper limit value, the overloaded channels are switched off. The
"Overtemperature Device" bit (index 0xF600:12) is set. All other channels continue to operate properly.
If the device temperature falls below the lower limit value the "Overtemperature Device" bit (index
0xF600:12) is reset. If the channel temperature also falls below the lower limit value, the respective channels
are switched on again.
Undervoltage (index 0xF600:13 [} 42])
If the "Undervoltage" bit (index 0xF600:13) is set, the supply voltage of the terminal has fallen below typically
17 V.
Voltage loss (index 0xF600:14 [} 42])
If the error bit in "Missing Voltage" (index 0xF600:14) is set, the supply voltage of the terminal has fallen
below typically 14 V.
EL28xx-xxxx Version: 2.2
Product overview
37