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  • Bob S BN
    replied
    Originally posted by HASA View Post
    I didn't want to install 36 additional inputs and 36 additional outputs if not necessary.
    You wouldn't need 36 additional outputs, I'm sure we all thought you already had these lights wired to 36 outputs. What Joe was saying was to wire the 36 "bypass" switches as inputs to the PLC, and program the PLC to activate output XXX when input bypass switch XXX is on.

    You didn't say why you needed to bypass the PLC program.

    If it's not for worry of PLC breakdown, instead of buying and wiring 36 switches, perhaps it might be more cost and time effective to install a CMORE micro, and program in the bypass switches on the display. Much less wiring this way.

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  • Bob S BN
    replied
    Originally posted by joe_haase View Post
    If you have anything other than a relay output, you can damage the output by backfeeding it 24 volts from another source. Your best bet would be to feed the switch into a input on the PLC, then do the switching through programming.
    Since it sounds like you're still open to picking output modules, as Joe mentioned above, choose RELAY output modules. These are mechanical contacts, and will not be damaged by backfeeding power.

    Originally posted by bcarlton View Post
    Use a two contact switch NO and NC. Wire it to disconnect the output from the PLC before connecting the light to power. If the output is inductive at all (relay or solenoid) be to add a diode across the load.
    Also, what Bernie is hinting at above, is choose a switch with a Normally OPEN contact as well as a Normally CLOSED contact for your light switch, and wire to disconnect from the PLC when switching on manually.


    You were going to buy 36 switches anyway, you just need to buy the right kind and wire appropriately, or use relay output modules.

    Good Luck,
    Last edited by Bob S BN; 04-26-2011, 07:34 AM.

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  • HASA
    replied
    Hasa

    Thanks for the replies. Two additional points to consider, the 24 vdc is the same source, and this issue pertains to 36 switch/light combos, I didn't want to install 36 additional inputs and 36 additional outputs if not necessary. Would the output module (co-16TD1) be damaged if backfed 24vdc from the same source?

    Leave a comment:


  • bcarlton
    replied
    Use a two contact switch NO and NC. Wire it to disconnect the output from the PLC before connecting the light to power. If the output is inductive at all (relay or solenoid) be to add a diode across the load.

    Leave a comment:


  • joe_haase
    replied
    If you have anything other than a relay output, you can damage the output by backfeeding it 24 volts from another source. Your best bet would be to feed the switch into a input on the PLC, then do the switching through programming.

    Leave a comment:


  • HASA
    started a topic Click ouput question

    Click ouput question

    I have a click output module that lights a 24 vdc indicator when the program calls for it, what I would like to do is add an override switch that would connect the same light directly to the same 24 vdc, does anyone see a problem with this ? if the output does not call for the light on, the manual switch could be used to turn on the light, placing the 24 vdc on the output of the module. would this cause any problems with the output module?

    Thanks
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