June 16, 2018 at 1:13 pm #2453
I am wiring +24 Vdc “Pneumatics Directional Control Valve Solenoid” with Micrologix 1400 PLC.
It doesn’t say it is PNP or NPN. Could you please help me to understand it ?
I have attached screenshot of the wiring for solenoid.June 16, 2018 at 1:37 pm #2455
Look at attached wiring diagram.
Please verify that it is correct.
RajJune 16, 2018 at 2:07 pm #2458
Pnp and Npn mainly refers to the input modules. Output modules are mainly relay outputs. So when you turn on the output what you have wired as a source voltage will be what is on the output you turn on. So using your drawing you have a +24Vdc source, and when you turn on any output you will see +24Vdc on it. Now by the diagram on the solenoid you need pin 1 wired to the output and pin 2 wired to common. The last pin is the ground. I hope this helps.June 16, 2018 at 2:29 pm #2459
Thanks a lot !
Could you please tell me “Why pin 1 goes to Output & not to common ? ”
I want to understand diagram on solenoid.June 16, 2018 at 2:42 pm #2460
I am going by the diode symbol on the solenoid. The anode must connect to the positive source and the cathode must connect to the negative. I circled the diode I am talking about in the attachment below.June 16, 2018 at 2:48 pm #2462
<p style=”text-align: right;”>If you were using an ac source it wouldn’t matter which is on pins 1 and 2 because it is an alternating signal from positive to negative. Both pins are going to get the same signal with ac source.</p>June 16, 2018 at 6:44 pm #2463
Fred (a.k.a. PLCGuru)Keymaster
Just want to add my two cents…the PNP/NPN discussion is always an interesting one (…possibly a topic for a new article…any takers?). Anyhow, current sinking input modules are a common North American standard as are current sourcing output modules. Some European countries as well as Asian tend to go the other way (current sourcing inputs and current sinking outputs).
While relay output modules provide good flexibility, particularly when you want to put different voltages on them, they are not the only option. Relay output modules are mechanical devices with limited switching times and life span. Often one failing relay output means you have to replace the whole module (or at least move that wire to one of the unused spares on the existing one…that’s always fun to find out!) So it is quite common in some circumstances to use solid state transistor or triac based output modules depending on the application.
Raj it looks like you’re well on your way to getting this sorted as there has been some really feedback here. Of course if you have any more problems be sure to check back in!
FredJune 17, 2018 at 9:16 am #2464
That is some great detail Fred thanks!June 17, 2018 at 1:43 pm #2549
Thanks all !June 22, 2018 at 4:42 pm #2701
Phi BachParticipantKarma Points: 18Rank: Padawan
PNP is sourcing and NPN is sinking .
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