first question to ask before set up?

[Smartguy]

Hi all I m really impresed by this forum. this is my first post on it. I m a student and new in this technology. I have one question. lets say, i m hired at some industry. they wanna use PLC so i will be doing all set up and programming. so wat will be my first question to them? what is that important thing i will need to know first?? guys plz help out!!!! thanks to all bye smart guy

[Smartguy]

:*-( plzzzzzz guys!!!!! i m lost whats a first thing to know about company before doing anything? is it their buget?? is it cycle time??

[Steve Bailey]

The first thing to remember is that a PLC is only one of many tools you need to able to use if want to automate your process. Knowing how to program a PLC is useless if you can't tell a solenoid valve from a motor starter or don't know how to choose from among proximity switches, photocells, limit switches, etc. If you already know all there is to know about PLCs, then you can consider them a commodity and select a brand on the basis of price alone. If you're a beginner and are likely to need a lot of support to get you going, then you should be asking which electrical products distributor in your area has already established a relationship with your company and is willing to guide you through the learning process. Then buy whatever brand they sell and let them help you make the right selection for your applications.

[Chris Elston]

Ask for the electrical spec. Most places standarize on PLCs and want you to use that brand only in their facility.

[Smartguy]

the company is not using PLC at this moment. they have no idea about plc thatswhy they hire me to do all things. i will be deside which plc to use. but my question is which things i need to know from them about company which will deside further progress in project..... ??

[Steve Bailey]

If you're joining a company that has done nothing to automate their production, there will be plenty of opportunities. Your challenge will be to develop an overall strategy and to prioritize. So, if there is a single question to ask, it would be "What do you hope to accomplish?" That establishes your goals. Then you need to develop a plan to get from where you are to where you want to be. Your first projects will be the ones that promise the best return on the time and money invested.

[Smartguy]

Thanks for ur reply guys! The most important thing I feel about setup the control system in the company is: " switchin time" all depend on it.. u can deside the type of plc and microcontroller later on.... if the switching time is less u can use relay or if fast then use microcontroller

[Chris Elston]

Don't go down to your Electrical Distrubutor and say "switchin time". That might show your age... In a PLC that is called "Scan Time" How fast the PLC can evaluate inputs, process and update outputs. Allen Bradley SLC family is among the slower scan time PLCs and Omron, Mitsubishi, GE etc...have faster scan times. It depends on what your doing, but if your doing simple Digital I/O scan time in an PLC doesn't affect much of anything, unless you put a bunch of timers in a step squence to slow it down.

[Guest rswolff001]

first thing to ask is application. that means I/O type and quantity, connectivity to other devices (serial, digital, DeviceNet, Profibus). Once you know that, you can start to decide which manufacturers will work and which won't. As an expample, if they need 200 digital I/O points, don't use a brick!!!. If they need to connect many units together pick a model that does this naturally (Allen-Bradley Siemens, Modicon, GE would be my choices). Do you need to connect to other devices or plc's? then what type? what kind of protocols? Do you need online programming? Then don't use an older GE 90-30. If this is you're first foray try to stay with something simple. Machiney and process controls can be involved and many times require knowledge of safety protocols and proceedures to ensure the equipment is operated in a safe fashion. Start with a small project so you can familiarize yourself with the hardware and software. Ask for software you can try for a week or so. Some software is easy to use, some will make you wonder why anyone would buy it. The cheap stuff is often the nastiest, with the most convoluted or non-existent documentation and minimal functions. Most of the time you get what you pay for. Bob

[Chris Elston]

Awe....what's wrong with the 90-30 I still like em.

[BobB]

90-30 is still OK. Can't say the same for Logicmaster 90. Bloody awfull.

[Steve Bailey]

BobB, why are you still using Logicmaster? There are alternatives. rswolff001, what do you mean when you say you can't do "online programming" with older 90-30s?