Virtual Relays and Holding Circuits for PLCs (Full Lecture)

In this lesson we'll examine virtual relays, software generated holding instructions, and the set and reset functions offered by most PLC programs. We'll learned that virtual relays mimic the behavior of traditional hardwired relays in that their associated instructions respond to the logical state of the virtual coil that can be energized or deenergized by the logic in a particular rung. We'll learn that virtual relays can extend the permissible number of contacts in a rung and be used to facilitate holding circuits, among other functions. We'll additionally examine software generated holding instructions that mimic the function of auxiliary contacts in that they respond to the logical state of a particular output that can be energized or deenergized by the logic in a particular rung. Finally, we'll examine the set and reset functions that selectively energize or deenergize an output and maintain this last asserted state until instructed otherwise. (Full Lecture)
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For more FREE online technical training check out the following playlists available at the bigbadtech channel:
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[@rudesback5013]

This channel really made PLCs easier to understand and much more intuitive

[@wowsuchhandle]

Amazing engineering videos without the indian accent, it's pretty rare to find on KZbin thank you.

[@khalman9089]

hahaha

[@Logical_Controls]

Ridiculously underrated channel. I haven't had any formal or professional training when it comes to PLCs, I just sort of picked it up from others at work and seem to have a knack for it. I wrote a program about a month ago and needed like 7 contacts all in series, funnily enough the first thing i tried was the backwards wiring haha made sense in my head at the time but it didn't work on a schneider smart relay so then opted for the virtual relay method. You've got a great PLC series going on. Thanks a lot from the UK.

[@gyrgrls]

For decades, the thing that has thrown me off the most about PLA's and PLC's is the terminology. Even the schematics of old EM pinball machines were split into two formats: the actual schematic and the ladder diagram. This is how ladder logic was born. I always found it easier just to write a truth table to a PROM. Then in the 70's we had CPU's like the 6502 or 6800. Now we have Arduinos. Dedicated PLC's seem commercial and superfluous.

[@adisharr]

Excellent lectures by the way. These are some of the best I've seen.

[@rayflint261]

You my friend are a true wordsmith. For this I’m extremely thankfull

[@brianvanheugten1796]

Amazing Lecture! You have amazing teaching skills. Keep up your hard work!

[@michaelcostello6991]

Good lecture. Thanks you

[@beznerwow1948]

You did great - thanks 😀

[@burakayan3360]

awesome lecture.

[@johnmilsom2179]

Great lecture ty

[@ilsemiller6376]

i love how you persist and maintain the terminologies used with different things....And not skip from one to another. it sort of embeds it into memory (atleast for me) when i think back on your videos. great channel.. question: the N/C on I1 presents as a N/O contact on the rung.. and the N/O on I2 also presents as an open contact but on input I2. is this correct? how do i diffuse the confusion with these? I'm fairly new to PLC's but have electrical experience and schematics, but this boggles me a bit

[@bigbadtech]

Check out the "Basic PLC Instructions" lecture at: kzbin.info/www/bejne/n5SclKWJi7t5b7M Long story short there is a difference between the electromechanical nature (ie: NO vs NC) and the programmed instruction (make vs break) and you are free to choose which combination you want.

[@adisharr]

The contact limit you talk about must apply to programmable relays. I've never seen that in any other PLC unless it's very old.

[@ledickin69]

Damn that was good! Txs

[@Time4yes]

Everytime time when I think of latching, I would stress on how does I1 which is normally closed gets back to its original state after being pressed to stop the continuity. So thanks for explaining the spring and cylinder process.

[@styxhisdicksahammerdyxdyxd8467]

Your videos are amazing thank you! Are you an electrical engineer?

[@bigbadtech]

A handsome one.

[@anismahmud3636]

nice

[@bayumartiesrizaldo1290]

hi jim, i'm bayu nice to meet you. can you help me, i'm beginner for plc and i want to build displays screen on commonly monitor (output) with sensor to count. by the way nice video.

[@adisharr]

I would avoid using 'safety' in any context unless referring to a safety rated system. I still see people trying to use standard PLC's for safety operations. At least explain that this is not a true safety rated system.