studio 5000 - oil pump to start motor

hello all,
i am new here and to the plc: i have Studio 5000.
i wanted to program an oil pump: i am using a low-level and a high-level sensor. then i want to use an internal relay which, upon activating, should turn pump oil into a motor to turn it on.
on the first rung: input (low-level) + input(high-level) + output (internal relay)
on the second rung: input (internal relay) + output (motor start)

my questions are:

- where do i find internal relay?
- and, am i on the right track?

many thanks,
karim.

Hi and welcome to the forum.

As for your question about the internal relay: That is just another way to discribe a Bool tag that is not connected to a physical I/O point. So you just create a Bool tag call it what you want and that is your internal relay.

With the level sensors (I assume they are just switches in the tank) you need to decide how you will be wiring them (NO or NC). I recommend NC so you will get a 1 when the tank is NOT at HL or at LL. This will add safety to the system if a switch fails or a wire is cut or diconnected in any way.

So you would want your logic to look more like this:
If NOT high level and NOT low level and internal then output

Of course there is more to it but this should get you moving in the proper direction.

Thank you Bullzi very much, and also for your great help.
Could you please have a look at my attachment (screen capture) and comment on it? I did look for errors and it gave me 0 (zero); but when tried to download it to controller, said to me to it is faulty and I should look for where the errors are.
I appreciate your help.
Karim.

First off why would you want to "seal in" the low_level level signal? That will allow the Internal_Relay stay ON even if you have a Low_Level. Is that what you want?

Next I see I may have confused you with my previous post. As I said before you should WIRE up the level signals as a NC connection. So you will get power on the input as long as you DO NOT have a Low_Level or a High_Level. So you want to use XIC's instead of XIO commands. In your logic.

Last I think you will need some type of input to start the motor. A button or a switch? The way you have it written if you don't have a LL and don't have a HL then the Motor_Run is on. So it will be on all the time is that what you want? Normally there is a input of some type to start and stop the sequence.

Give it some thought.

I think he's wanting the low level to turn on the pump and the high level to turn it off. My thought is " why the internal relay? The way it's written, the internal relay OTE could be the motor OTE and save a ring of logic.