Beginner needs help

[larsUSA123]

Hi, my name is Lars and I am new to the site. This site has had a lot of useful info. I am a new engineer that is now in projects. I am responsible for coming up with estimates for plc programming projects. Does anyone have any secrets or rules of thumb to determine the cost of writing plc programs based on the numbers of discrete i/o, analog i/o and speciality modules (high spd counters, servo modules). I realize a lot of this is based on experience, but since I am a recent grad, I don't have the experience. Can anyone help?

 

[Mickey]

See links below for a couple of threads that have discussed the topic.

http://www.plctalk.net/qanda/showthread.php?t=31584&highlight=cost+writing+plc+programs

http://www.plctalk.net/qanda/showthread.php?t=7340&highlight=cost+writing+plc+programs

 

[ndzied1]

Whatever you come up with for a programming time, double it. Then you won't undershoot the time too much

The only real way to quote programming is to have a specification for the job. More often than not, the customer will not have one (at least in my experience) so the estimator has to come up with one themselves.

Without a specification, you are likely to spend much more time than originally estimated because the customer's idea if when a machine is done usually includes every whim and extra bell and whistle that pops into their mind during the start up. Many of these are good ideas and will make the machine better but unless you spell out the features included (and not included) at the outset, you'll be doing them for free.

 

[bhaskar.bose73]

My experience tells me: count for the application, process or batch, process is easy, batch is repetative (time consuming), number of graphic pages, number of engineering tags, number of function blocks, no. of tunes ( adoptation) at site,
just an idea: for a simple application.

di= two internal bit= 10 min.
do= three internal bit, one physical bit= 15 min.
ai= five internal bit= 20 min.
ao= seven internal bit=35 min.
PID= 8 internal bit= 35 min (engineering) 1 to 2 hrs ( on site). depending on loop responce. High speed pressure, or low speed temp.

any additional function block= 25 to 30 min each.

graphic:

average, 100 to 150 dynamic tag per page,
1 page= 5 hrs.

hope this helps, you can fine tune your experience after this.

any way, for quotation purpose, consider: 7% of your sale value as your engineering cost. ( if the customer has a clear cut control philosophy, otherwise load 15%).

Thanks

Bhaskar