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LOGO! 8 INPUT PIN MAX. CURRENT LIMIT

Created by: plcembedd at: 6/16/2019 6:27 AM (5 Replies)

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6/16/2019 6:27 AM	Rate (1)
plcembedd Posts: 8 Rating: (3)	Hi all experts, Please excuse me if my question is silly but from the datasheets i found that the Typ. current input to a digital input is 1.5mA but (as shown in manuals, datasheets also) we connect switches between 12V and one of the inputs of PLC i.e., directly. So I want to ask what is the maximum permissible current input to any digital and analog input to my plc (LOGO! 8 12/24 RCE) so that I can apply a necessary resistor or fuse to the inputs. OR it is OK to connect switch or sensors etc directly to the inputs of the PLC? Thanks and regards
plcembedd Posts: 8 Rating: (3)
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6/16/2019 6:52 AM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 12/1/2024 Posts: 34320 Rating: (4274)	plcembedd OR it is OK to connect switch or sensors etc directly to the inputs of the PLC? So it is. Only the supply voltage is protected, not every input, sensor etc.

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6/16/2019 8:29 PM	Rate (1)
plcembedd Posts: 8 Rating: (3)	So can I connect sensors, switches etc to the PLC input without worrying about the input current just care about the sensor voltage 12/24V in my case for logo8
plcembedd Posts: 8 Rating: (3)
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6/17/2019 11:02 AM	Rate (2)
LOGO! Support Gold Expert Joined: 9/19/2018 Last visit: 11/28/2024 Posts: 399 Rating: (47)	As long your sensor fulfills the requirements you find in the manual, you can connect it directly to the LOGO! input. For LOGO!12/24RCE: “low” is measures for: <5 VDC and <0.88mA (I3 to I6) and <0.07mA (I1, I2, I7, I8) for “high”: >8.5 VDC and <28.8 VDC and >1.5mA (I3 to I6) and >0.12 mA (I1, I2, I7, I8)

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6/18/2019 7:33 AM	Rate (1)
plcembedd Posts: 8 Rating: (3)	Yeh thanks as you also written (and the manual says) for “high”: current >1.5mA (I3 to I6) and >0.12 mA (I1, I2, I7, I8) so we need not worry for over-current protection we can have any value > 1.5mA(I3 to I6) just care about over-voltage protection : voltage must be <28.8 VDC Isn't ?
plcembedd Posts: 8 Rating: (3)
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6/18/2019 9:38 AM	Rate (1)
LOGO! Support Gold Expert Joined: 9/19/2018 Last visit: 11/28/2024 Posts: 399 Rating: (47)	Yes

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