Dear All,

we have the 2-wire inductive switches N.C (NBN4-V3-N0-Y51517/P+F) installed in the Positioner mounted on the valves for feedback, the switches normal operating Voltage are 8VDC to 16VDC that could not be fisible to directly operate the PLC Digital Input. Please solve this issue that we could operate the PLC Digital Input with thoes switches.

we are using Mitsubishi FX1N-40MR, and the SS point connected with the -VE/24VDC

we have tried to wireup them with an optocoupler (TLP521-1) in simatic but still invade.
if anyone have the idea, please share it with me.

thanks and best Regards

Hi,

You should connect this sensor to PLC via relay. And because this sensor much time is in NC statement, the better to use a optocoupler type of relay.

I think more cheaper will be to change the model of inductive sensor.

we have tried to wireup them with an optocoupler (TLP521-1) in simatic but still invade.
if anyone have the idea, please share it with me.

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Please read quoted above.

If you:
1) wired LED circuite with right polarity and with load resistor, which is equal to 1 kOhm at 16VDC,
2) wired SS circuite to minus of power supply, collector to plus of power supply, emitter to PLC input
TLP521-1 must work properly.

please see the attached image, whom i have been working on it but not functioning. Please mention if there would be changes to made.

If you don't have a lot of inputs you can change them to NPN instead of PNP and the input would switch on 0 volts instead of 24. 16 Volts should be enough to turn the input back off. What kind of switches are you using that won't work at 24 volts? I've never seen a prox switch that was rated for less than 24 volts. Oh, also some 2 wire prox switches need a good sized load to "turn them on". The input circuit in the PLC is not enough to do it and a Solid State Relay isn't either. Use a standard relay and it will probably work. I've run into this a few times as well.

Dear Muhammad,

Your TLP521-1 was damaged by you... The maximum current for LED of TLP521-1 is 70mA. You used 100 Ohm resistor, and your operating current was equal to 12V:0,1kOhm=120mA.

Dear 'Duffanator',

It's impossible to solve this problem with the source input connection (which you named NPN). It's impossible to use relay with standard coil too, because it will work constantly and will be damaged very quickly. Already I have adviced him to use optocoupler relay (which you named solid state) or to change his 'wrong' sensor onto sensor with normal power supply. But alas now he has serious difficultes and would like to have serious problems with equipment in future. This is style of life!
In russian exists good byword: "Seven times to mete, one time to cut".

Hello. The induktive switch you refer to is an old NAMUR type. It operates on 8VDC. Link to sensor : http://www.pepperl-fuchs.co.uk/cps/rde/xch...CBA21F-6AB14ACA

It's inteded for use in explosion hardious areas. You need a isolated barrier, go to : http://www.pepperl-fuchs.co.uk/cps/rde/xch...ker.htm?force=1

Then it should work.