LG LS PLC proximity inputs, PNP or NPN?
LG LS PLC proximity inputs, PNP or NPN?
(OP)
I have been given the task to buy an LG PLC (K120s)20 to 40 I/O, I need to input some proximity switches, do I use PNP or NPN, I want to use the inbuilt 200ma 24v power supply, I'm getting old and have forgotten all I knew about transistors as I haven't done a lot with them, I can plod my way thru writing a ladder program for it but not sure on the inputs.
Input specification
On voltage/current DC19V or higher/5.7mA or higher
Off voltage/current DC6V or lower/1.8mA or lower
Input impedance About 3.3㏀
I want to use the inbuilt 24v power supply negative to common on inputs for stop start push buttons, but not sure which proximity's to buy?
Thanks in advance
http://eng.lsis.biz/product/product/file_download.asp?download_id=881&intFile=1&refer_product=third_down_view.asp&catlev3_id=13
Input specification
On voltage/current DC19V or higher/5.7mA or higher
Off voltage/current DC6V or lower/1.8mA or lower
Input impedance About 3.3㏀
I want to use the inbuilt 24v power supply negative to common on inputs for stop start push buttons, but not sure which proximity's to buy?
Thanks in advance
http://eng.lsis.biz/product/product/file_download.asp?download_id=881&intFile=1&refer_product=third_down_view.asp&catlev3_id=13





RE: LG LS PLC proximity inputs, PNP or NPN?
It also means that you shall connect push button common to +24 V. Negative won't work. All inputs need "sourcing" signals, i.e. signals that go high when active.
Using the internal +24 V is good. But you will have to consider total load. If the inputs draw 5.7 mA at 19 V, they will probably draw just above 7 mA at 24 V. Check if your total load is within the 200 mA of the unit.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: LG LS PLC proximity inputs, PNP or NPN?
This is the sensor I am trying to use, it is NPN
http://cgi
However I have searched and found this info on the PLC, whoops, I will have to shut down and add another post to finish this one..........
RE: LG LS PLC proximity inputs, PNP or NPN?
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and on page 75 of the pdf is says this
3) Input wiring
Main unit's wiring method is as follows. DC input specifications offered by MASTER-K120S is to be used for both electric current sink and electric current source.
It also shows the inputs broken up into 2 banks, I wonder if I can SOURCE one lot for push buttons and sink the other lot for NPN proxys?
RE: LG LS PLC proximity inputs, PNP or NPN?
So, you are free to use almost any configuration you choose. But, I would prefer to use the standard configuration with PNP and sourcing switches for all inputs. That gives you a fail-safe function and much less confusion. Same rule applies to all input. Makes life easier.
There are PNP devices available from the vendor you referred to.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: LG LS PLC proximity inputs, PNP or NPN?