Estimate time to Program a PLC

What rule of thumb or SWAG do you use to estimate how long it will take to program a PLC?

I/O count?

Operator Interface screens?

Help!

Thanks
John

re: hours

Hello,

When I have quoted for projects I have used the following numbers as an approximation (dependent on complexity of system)

1-2 hours per I/O point
4 hours per PID set-up
4-6 hours per standard HMI screen (i.e. Panelview)
6-10 hours per SCADA or graphical user interface screen (i.e. Wonderware)

After that it all becomes a judgement call on complexity of system or graphics, experience at software package, experience at system, how many reusable code segments from previous similar projects, etc.

I break the project down into smaller tasks. Some of the tasks will be similar to things I've done in the past, so I can make a more accurate estimate. On the tasks that I haven't done before, I estimate conservatively. Then I add up the times for all of the tasks.

Now comes the tricky part. I'm going to multiply that time estimate by a contingency factor that may range anywhere from 1.5 to 5. The things that go into the contingency factor include, how well I understand the client's needs, how good is the specification, how busy I expect to be while I'm doing the work, how much I want this gig, etc, etc. Don't forget to include time for meetings, phone calls to clarify things, rewrites because you misinterpreted the spec.

Wahtever method you use, be sure to keep accurate records of the time you spend doing the work and compare the actual time to the estimated time. That way, future estimates will be more accurate.

Thanks guys that gives me a place to start...


Have a good one...

Re: re: hours

Screamin said:

Hello,

When I have quoted for projects I have used the following numbers as an approximation (dependent on complexity of system)

1-2 hours per I/O point
4 hours per PID set-up
4-6 hours per standard HMI screen (i.e. Panelview)
6-10 hours per SCADA or graphical user interface screen (i.e. Wonderware)

After that it all becomes a judgement call on complexity of system or graphics, experience at software package, experience at system, how many reusable code segments from previous similar projects, etc.

Click to expand...

My personal feeling is I don't charge much if anything for learing software. That is the way I did it when I programmed databases. I sleep better at night if I learn on my own time...

Wadduthink?

I personaly do not quote only on the I/O basis. The way I do it is :

The cost of the hardware x 2.5

+

10% net sales price...for surprises
-------------------------------------------------
Ex:

Typical PLC + Web server panel = 30K

I would price it at:

30 x 2.5 = 75

Hardware would sale at 30 x 1.30 = 39

So my sale price would look like, (39 + 75)*1.1= 125k
-------------------------------------------------

This includes:

CADs drawing with sources AND blocks.
Panel assembly and wiring and shop testing.(CSA approved)
Email server setup and testing.
Flowcharts and Karnaugh maps.
PLC program pretested in the shop (including sources) with MANY comment (every lines at least and more)
Instruction manual on install and commissionning.
HMI and 1 Web page.
Small maintenance datalogging rung (less than 10 variables x 100 logs, 1000 registers)

The overall cost of the PLC prgramming is around 30K so it matches the hardware cost BUT it cannot exist by itself. you cannot price programming alone because you need a lot more in order to be able to do this program.

These are rough numbers and they do vary from time to time but when in front of a client, I know to plus or minus 10% how much my quote will look like.

BEWARE OF QUOTES FOR PROGRAMMING ONLY They could make you eat your shirt.

I only quote on custom system with High technicity, a less technical system would certainly go for a lot less, this is my niche.

Re: Re: re: hours

jthornton said:

My personal feeling is I don't charge much if anything for learing software. That is the way I did it when I programmed databases. I sleep better at night if I learn on my own time...

Wadduthink?

Click to expand...

Well there is a number of ways I look at it. In a pure time and material project, I would probably not charge very much for "learning time". That's were sometimes the company must "suck up" training costs in order to keep employees and be better prpeared for this and future projects. In a quoted project, I would evaluate just how much potential money is on the table. Regardless of the project that you are doing, there will almost always be a learning curve involved whether it be software or system or design. Its also very customer dependent. A few of my previous customers were very forward thinking in that they realized that it is impossible for any one person to know everything (except for my wife, of course). They were more then willing to offer time for the technicians to review and become familiar with the software or code. This was due to the fact that they were experienced commissioners and that was what they were hired for. The customer knew that after a couple of days of learning, they would have the best technicians working on their project. Hell, we were even able to get our client to pay for formal training for some of our technicians.

it is impossible for any one person to know everything (except for my wife, of course)

Click to expand...

And I was certain that my dear one was a unique model

Pierre said:

And I was certain that my dear one was a unique model

Click to expand...

Unique! Sorry Pierre but that's impossible, you see when the Lord made women he ran out of idea's, so he thought "oh well, not a problem really, nobody will notice!" Little did he know that a few thousand years after he made them, modern technology would give us the ability to communicate over vast distances, thus discovering that Screamin's wife is the same as your wife, and my wife and .........................
well, just about everybody's wife!

I only charge for "learning time" on programming when I am using a new platform specifically at a customer request. Then it is priced accordingly into my quote - the rule is no surprises for the customer.

Tom Jenkins said:

I only charge for "learning time" on programming when I am using a new platform specifically at a customer request. Then it is priced accordingly into my quote - the rule is no surprises for the customer.

Click to expand...

That I agree on. If i have to learn a system at the customers request they pay me to do so. I recently had to learn a machine in the plant to write a new PLC program for it (the old one had too many hands in it) so I charged them by the hour to trace every thing out on the machine...

by suprises you mean cost to the customer??? have you had a learning experiance with a customer that you can share??

John

John

Do you go by another name?

Somebody else is asking the same question

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