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Rockwell Automation Publication 856T-UM001B-EN-P - April 2021
Appendix D Device Status
Short Circuit
The firmware of the 856T-B24LC module disables the entire stack light when
any of the circuits demands a load current that exceeds 450 mA ± 15% of
current (at least for 40 ms) and is less than 4.5 A ± 15%. In this case, the first
circuit that was detected to cause the short circuit is indicated by its respective
bit number in the short circuit status byte (ISDU= 0x014C 332). Also, the bit
representing that a short circuit condition exists is indicated in the Alarm
status word (ISDU= 0X0135/ 309).
Since the entire stack light is disabled during a short circuit, the
(ISDU=0x0136/ 310) Control Circuit status reports OFF for all circuits when a
short circuit condition exists.
The short circuit status bit only clears when you attempt to turn the circuit
back ON and the short circuit is no longer present.
If the short circuit condition exceeds the 4.5 A ± 15%, then a dead short occurs
and the 856T-B24LC hardware detects it, all outputs are disabled, and the short
circuit status is reported for all the outputs that were ON when the short
circuit occurred. This short circuit detection takes priority over the firmware
detection explained previously.
The short circuit status bit only clears when the short circuit is no longer
present and you attempt to turn each one of the circuits involved back ON.
IMPORTANT
The 856T-B24LC short circuit performance may vary depending on the
IO-link master used. For example, a master with rapid short circuit
protection may disable the 856T-B24LC before the short circuit
detection in the 856T-B24LC base takes effect.
IMPORTANT
Remove incoming power before you check connections or replace light
or sound modules in the stack. If you replace one or several light or
sound modules when the respective circuit is energized at the time of
the replacement (hot swap), the situation may cause a temporary short
circuit condition that is indicated in the alarm status word. You must
clear the alarm bit to be in operational mode again.
Содержание Allen-Bradley 856T-B24LC
Страница 6: ...6 Rockwell Automation Publication 856T UM001B EN P April 2021 Table of Contents Notes ...
Страница 18: ...18 Rockwell Automation Publication 856T UM001B EN P April 2021 Chapter 2 IO Link Overview Notes ...
Страница 72: ...72 Rockwell Automation Publication 856T UM001B EN P April 2021 Appendix D Device Status Notes ...
Страница 76: ...76 Rockwell Automation Publication 856T UM001B EN P April 2021 Appendix F Troubleshooting Notes ...
Страница 80: ...80 Rockwell Automation Publication 856T UM001B EN P April 2021 Index Notes ...