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output module manually drive to high

Created by: Bofely at: 9/20/2012 11:54 AM (5 Replies)

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9/20/2012 11:54 AM	Rate (0)
Bofely Posts: 123 Rating: (5)	Hello, If my PLC logic drive a digital output to 0V and I manually put 24V at the digital output connection. Would this damage my card? Module diagram is included in the attachment. ( 6ES7322-1BL00-0AA0 ) Is there a output module that can work with this situation? Thanks, Attachment output module.jpg (76 Downloads)
Bofely Posts: 123 Rating: (5)
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9/20/2012 12:04 PM	Rate (0)
Marcjan Platinum Expert Joined: 4/22/2010 Last visit: 5/3/2024 Posts: 5697 Rating: (715)	Hello, I suggest to place a diode between output and load to prevent reversed current to output transistor. All cards with redundant capability have build in Diode for that reason. Relais cards, don't care about that at all. Regards, Marcjan Attachment DO-redundant.pdf (67 Downloads)
	Last edited by: Marcjan at: 9/20/2012 12:27 PM Attached example Problem solved? Please let us know! Please no technical questions by PM, use the forum sections for your questions.
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9/20/2012 12:33 PM	Rate (0)
Bofely Posts: 123 Rating: (5)	I don't see how it's possible to have a reverse current. I don't know what kind of transistor is in the modules. But let say it's a bipolar npn transistor. Collector to L+ and emitter to output connection. If logic 0 at base and 24VDC (manual switch) at output connection, where do we have a reverse current?
Bofely Posts: 123 Rating: (5)
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9/20/2012 12:41 PM	Rate (0)
Marcjan Platinum Expert Joined: 4/22/2010 Last visit: 5/3/2024 Posts: 5697 Rating: (715)	Hello, In theory not , you're right, but have seen strange behaviour with sensors (transistor output too)connected the same way as you like to do. So better invest a few cents for Diodes than be sorry afterwards. Regards, Marcjan
	Problem solved? Please let us know! Please no technical questions by PM, use the forum sections for your questions.
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9/20/2012 12:48 PM	Rate (0)
Bofely Posts: 123 Rating: (5)	Thank you. I will consider it.
Bofely Posts: 123 Rating: (5)
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10/5/2012 3:40 PM	Rate (0)
Bofely Posts: 123 Rating: (5)	Price is just one of the aspect. The other is using standard module. I want to use: Interface module - UMK 45-DO/LA/SIM 8 - 2968195 This one fit perfectly with a standard io module (not safe/ no relay), if I connect this with a ribbon cable to the interface card(System connectors - FLKM 14-PA-S300 - 2299770), then it's not possible to build a diode inbetween. I have tested the connection as I described here, it work. But I'm not sure if I can trust this behaviour.
Bofely Posts: 123 Rating: (5)	Last edited by: Bofely at: 10/5/2012 3:45 PM
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