Need PLC programing site!

edward4444 · Dec 23, 2006

There are websites where a person can post a coding job, for programmers to bid on it. Ultimately a programmer is selected and given the programming job based on his $ bid amount.
That's great... but the sites I see seem to be just for PC programming.
Where can I find a site for posting the requirements for my PLC programming job? I have a Siemens STEP5 statement list program that needs worked on, and I need to find a programmer to do it!
Thanks

sps-concept · Dec 23, 2006

S5

Hello,

what can i do for you? how many io? description?

Steve Bailey · Dec 23, 2006

You can post an ad in the classifieds section here. Click on "PLC Jobs" at the top of the page.

I'm right in your back yard, but alas, I'm not fluent in Step 5 nor do I have the software.

edward4444 · Dec 26, 2006

Steve Bailey said:
You can post an ad in the classifieds section here. Click on "PLC Jobs" at the top of the page.

I'm right in your back yard, but alas, I'm not fluent in Step 5 nor do I have the software.

Steve,

Thanks for the info. I posted the project at the page you suggested.

For those that have asked, here is some information on what the task involves:

PLC: Modify Siemens STEP5 Statement List program

Description
I have an existing PLC program running on a Siemens S5 PLC. The PLC is used to control a rotary machine that makes plastic bottles.
The machine is limited in the speed it can rotate. It can make approximately 40,000 bottles per hour. If the speed in increased much beyond 40,000 per hour, then the PLC program will shut down the machine.

On similar type blowmolding machines, data blocks are used to hold a constant value that is used as the upper speed limit. That is, HEX values of approximately 40,000 were found in data blocks. By adjusting these values, the machine speed upper limit was raised.

For THIS machine the code is different... not sure how the upper limit is being set.

Regardless, the project is to study the existing statement list code and identify how the machines upper limit is being set and to adjust the upper limit to 42,000

russrmartin · Dec 26, 2006

I also don't have step5 software, but this sounds like a very simple thing to find and alter. I don't know if it's even worth your time to bid this sort of thing. Unless someone REALLY tries to rip you off, this is something you should be able to get someone to do in a very short period of time. If you don't have anyone in house who can do this, I'd be looking to develope a good working relationship with someone who can do these pick and poke changes at the drop of a hat for you, preferably someone "in your back yard". Good luck.

Russ

Marc · Dec 26, 2006

Edward,

Nice to see someone in my neck of the woods. Alas, I am not proficient in siemens either. Too bad it wasn't some other processor. 40k bottles per hour, I think I may know where you are, southern NH?

If it's the place I am thinking of, I used to work right up the street.

Marc

10BaseT. · Dec 26, 2006

May I suggest that you choose your programmer on his merits , not necessarily the price - cheap is cheap if you pay once only .

I would NEVER bid on a job - if you wanted it done , it shouldn't be because I am cheap .

S7Guy · Dec 26, 2006

People don't always bid out a job to get a low offer. Sometimes they simply need a budgetary quote to even get the money released from the bean counters. I've done work by both fixed bid and by the hour, and it turned out OK on both sides in each case.

Tom Jenkins · Dec 26, 2006

10BaseT. said:
I would NEVER bid on a job

Must be nice!

Actually, I think the best technique selecting professional services for many kinds of projects is a combintation of pre-qualification and bidding. The first step is to solicit potential vendors and create a short list of those with the right qualifications, experience, and equipmnet. Then you can solicit proposals based on your pre-defined qualifications and encouraging alternate solutions. Always reserve the right to select someone other than low bidder. Then you select the vendor based on the combination of qualifications and price.

This doesn't work on small projects, since it involves a lot of work for both the customer and the vendor. On larger projects, though, it not only gets you a optimum solution, it keeps everybody honest.

For small projects I agree with my interpretation of 10BaseT's solution. Go with someone you know and trust.

edward4444 · Dec 26, 2006

Tom,
Yes, the technique you mention for projects is actually available online(at least for PCs)... there are sites specifically designed to bring together coders and customers for PC projects. Just have not found anything similar for PLCs.

Happily though, I am receiving some interest from people that just happen to read this thread.

bernie_carlton · Dec 26, 2006

OT: Since this isn't precisely on the poster's question:

Possible reasons why an upper limit to a machine speed is set in code -

1. To prevent damage to operating personnel - though I would not want to trust the safety of a software speed limit.

2. To prevent damage to the machinery due to mechanical limits the builder has already found?

3. To preserve production quality - which may become less at a higher speed?

4. To provide a window for an easy paid upgrade? (Maybe not since the area of the program wasn't protected.)

Any others?

If 1, 2 or 3 is the customer prepared to accept any consequences of the changes?

If 4 - is it right to change this limit without (presumeably) the supplier's concent?

Leadfoot · Dec 26, 2006

bernie_carlton said:
OT: Since this isn't precisely on the poster's question:

Possible reasons why an upper limit to a machine speed is set in code -

1. To prevent damage to operating personnel - though I would not want to trust the safety of a software speed limit.

2. To prevent damage to the machinery due to mechanical limits the builder has already found?

3. To preserve production quality - which may become less at a higher speed?

4. To provide a window for an easy paid upgrade? (Maybe not since the area of the program wasn't protected.)

Any others?

If 1, 2 or 3 is the customer prepared to accept any consequences of the changes?

If 4 - is it right to change this limit without (presumeably) the supplier's concent?

This questions definately need addressing. Most wheel drives on plastic bottle moulding machines are usually capable of going as much as 20% faster. Ususlly the limiting factor is if the extruder can push the material to maintain the thickness of the bottles.

I have seen many a co-extruder added to bottle makers and the wheels and drives do OK at the higher speed than original. OF COURSE, the questions Bernie asked were addressed before any mods were done and the machine owner/operator took full responsibility for the machine after it was modified.

JRW · Dec 26, 2006

Be leary of the programmers that say "oh sure..easy" and throw out a price before looking at your code.
Because I bet your program is
1) Commented in German
2) All STL
3) Alot of indirect addressing
4) Has the code for all the options this machine could possibly have.

Find a programmer/integrater that understands your machine too or at least wants to look at it run.

10BaseT. · Dec 27, 2006

edward4444 said:
Steve,

Thanks for the info. I posted the project at the page you suggested.

For those that have asked, here is some information on what the task involves:

PLC: Modify Siemens STEP5 Statement List program

Description
I have an existing PLC program running on a Siemens S5 PLC. The PLC is used to control a rotary machine that makes plastic bottles.
The machine is limited in the speed it can rotate. It can make approximately 40,000 bottles per hour. If the speed in increased much beyond 40,000 per hour, then the PLC program will shut down the machine.

On similar type blowmolding machines, data blocks are used to hold a constant value that is used as the upper speed limit. That is, HEX values of approximately 40,000 were found in data blocks. By adjusting these values, the machine speed upper limit was raised.

For THIS machine the code is different... not sure how the upper limit is being set.

Regardless, the project is to study the existing statement list code and identify how the machines upper limit is being set and to adjust the upper limit to 42,000

hold on - this one has been done - isn't there a password for the speed change ? I remember this one . I would be very surprised if the value of parts per hour was set like that - per second , or per minute , not per hour - though that isn't the imprtant thing - why does the machine shut down when the maximum speed is exceeded ?

Automation_Tech · Dec 28, 2006

edward4444,

Can you post your program?, someone should be able to look at it and give you a ball park figure, or help you, so you may be able to make the changes yourself, there are demo versions of S5 software that you can make edits with

Need PLC programing site!

edward4444

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sps-concept

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Steve Bailey

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edward4444

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russrmartin

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Marc

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10BaseT.

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S7Guy

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Tom Jenkins

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edward4444

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bernie_carlton

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Leadfoot

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JRW

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10BaseT.

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Automation_Tech

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