Omron C200HE-CPU11 Installation Manual page 155

Specifications
C200H-OD214 Short-Circuit Protection
The C200H-OD214 Output Unit is equipped with two types of short-circuit protection: overcurrent protection and
thermal protection. Any short-circuit must be eliminated immediately in order to avoid damage to the Unit.
Overcurrent Protection
When the output current reaches 2 A, the alarm output turns ON, and the alarm indicator lights. Make sure the
surge current of the load does not exceed 2 A, or the alarm may be activated.
Thermal Protection
When the junction temperature of the output transistor reaches its upper limit, the output turns OFF, the alarm
output turns ON, and the alarm indicator blinks. But the output transistor is provided with a heat sink. So in some
cases, when the output is short-circuited the thermal protection may not activate because the extra heat is dissi-
pated by the heat sink. However, the alarm indicator will still light and the alarm output will still turn ON.
How It Works
When the short-circuit protection activates, the output displays the characteristic shown below.
Each pair of outputs share one alarm indicator and one alarm output bit as shown below (bits 12 through 15 cannot
be used as IR bits)
Both the alarm indicator and alarm output bit for the short-circuited output turn ON even if only one of the outputs is
short-circuited. Both outputs should be disconnected until the short-circuit can be traced.
Clearing the Alarm
When the short-circuit has been eliminated, reset the Unit by pressing the reset button. The alarm indicator will go
out, the alarm output will turn OFF, and the output will be reset.
Programming Example
If there is a short-circuit in an output, we want the program to turn that output OFF. Assume that the Unit is mounted
at word 000. A program to turn OFF output bits 00 and 01 is shown below.
Since alarm output bit 08 covers both output bits 00 and 01, both these outputs are forced OFF as soon as output
bit 08 turns ON (bits A and B can be any other bits required in the program).
Output
Voltage
0
Output No.
Alarm indicator No.
Alarm Output Point No.
Output indicator
Alarm indicator
Reset button (use a screwdriver
or other similar object to press it).
A 00008
B 00008
Overcurrent
limit alarm
output point
Output current:
2 A (minimum value)
0 1 2 3 4 5 6 7
0 2 4 6
08 09 10 11
00000
00001
Appendix B
143