Homework help, will pay

Well I need someone to help me with a PLC problem (Siemens
S7-300 series) . I'll be willing to pay by Paypal depending on how you help me and stuff. so post your msns here if you want to help

Refreshing candor - let's see what happens.

What's the project en-stuff?

Well at least he is up front with his request...I can't bite 'cause I'm not a S-7 person...Maybe our long lost buddy Paul will pipe in...

David

Do you want this quoted? Or is this a T&M job?

If the later know that I charge overtime after 5:00 pm and weekends.

Here's what he wants

OP said:

Design sequence sewage system control
Make your design for the sewage lift station on the following sequence of operation:​

•​

All pumps OFF at the low level.​

•​

1st pump ON at the second high level.​

•​

1st & 2nd pumps ON at the third high level.​

•​

All pumps ON at the fourth high level.​

•​

Alarm signals shall be sent to the local control panel (light and audio) and to​

the control room.​

•​

When pumps are actuated they shell operate until the low level reached.​

•​

If one of the pumps is shutdown or switch off next pump shall be​

automatically selected to operate​

•​

The leading pump shall be alternated so that no pump shall have two​

successive starts.

Click to expand...

Hey, we've seen this assignment before!!!

up

If you have questions, why not ask your specific questions!? We will HELP you with your homework, but we won't do it for you. Show us what you have, ask specific questions, show some initiative on your own FIRST.

See the link in my sig.

If you can't/won't do that, then you're on your own...

i have difficulty in the last part of the assignment


successive starts.)

The last part is referred to as "Lead-Lag" operation (not to be confused with Lead-Lag compensation in Control Theory). You see this to distribute use over two pumps, rather than have one doing all the work 24/7.

One pump is designated the lead, one the lag (think of it as a back up). The lead always turns on first. When both pumps turn on at the 3rd high level switch, the lead-lag designation is swapped, so that the pump that was formerly the "lag" pump becomes the "lead" and will start up when the level reaches the 2nd switch (after the pumps have turned off again).

The lag is also becomes the lead should the lead be turned off or faulted.

I had the exact same program that I wrote in PicoSoft, which was the first program I wrote out of school. No one explained to me how what "Lead Lag" was at the time and I didn't have old code to look at so I basically had figure it out myself.

It really is a simple program though, you can do it with a relatively small amount of code too.

HINT: Make the lead-lag indication toggle when the above events happen (make it a bit or something). I thought that was the tough part of the program.

It can get a little more confusing when a 3rd pump is added to the mix (known as lead/lag/standby)

Danger said:

i have difficulty in the last part of the assignment

(The leading pump shall be alternated so that no pump shall have two​

successive starts.)

Click to expand...

Show us what you already have? Perhaps we can see the problem and help you correct it...

I love turds, i will do the assignment for free

Danger: Pm me

Ill post the program so everyone can see Is it Ld, STL or SCL ?

At least to make it clear you should do it in indirect STL

Thim said:

At least to make it clear you should do it in indirect STL

Click to expand...

I may have to ask the guru (LD) for help