Author Topic: Output state on powerup  (Read 10670 times)

Joel Moore

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Output state on powerup
« on: May 17, 2004, 11:22:47 PM »
Whenever I power up our T100MD888+ PLC some of the outputs get energized which in turn causes whatever actuators are connected to them to suddenly move.  In some cases this can be a problem.  Is there any way to control this?

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Re:Output state on powerup
« Reply #1 on: May 17, 2004, 11:46:56 PM »
Which output? Is it output 7 & 8? Some earlier batch of MD888+ may have this problem due but I learnt  that this problem has been eliminated in the later batches.

The best way of wiring up a control panel is to apply power in two stages using a multi-step rotary switch which will supply power first to the PLC and then to the load. When powering down the power to the load is first disconnected, then the PLC. That will prevent any undesirable glitches during startup.
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Joel Moore

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Re:Output state on powerup
« Reply #2 on: May 18, 2004, 07:20:08 AM »
In this case it's output 4.

Hmmm...maybe instead of a rotary power switch I could achieve the same goal with a timed relay.  However, either technique will require a different wiring strategy which isn't all that feasible with the current machines I have built.