lololovelola

Can anyone guide me on how to choose a PLC?

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Hi,

This is my first time to start an actual project. I have some basic to intermediate programming background with Seimens PLC in the past but with no work experience.

I bought an old bandsaw machine for a very cheap price. It works fine on manual operations but I want to try and test if I can make the fully automatic function back. The current PLC installed in the machine is a Shihlin Electric SEPLC A1-30MR. It look old and the port is not familiar to me. I also have no idea if I can even get the program inside or not. Thus, I plan to replace the old PLC with a new one.

Here are my questions. Should I use a PLC or can I just use a digital controller like Logo ? I need to use a loop for counting how many cuts it should do. And how many times the machine should repeat the push of my stock out per cut.

What else should I consider when choosing a PLC or digital controller?

 

Thank you in advance. :-)

SEPLC A1-30MR.jpg

Port.jpg

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A1 is equivalent to Mitsubishi F1.  Obsolete decades ago, no software, if you don't have the face-mounted programming console, you're not going to get the program out.  Assuming the battery isn't dead and the program already gone, which is highly likely.

Siemens Logo is not a PLC.  It's a smart relay.  It may be able to do what you need.  I used them a decade ago, and still have one in my Halloween props. 

Everyone has a small PLC like this.  Omron CP, Mitsubishi FX, AB Micro, Siemens S7-1200.  My recommendation would be write up exactly what you want from it, and then look at a PLC that you would be comfortable programming from scratch for your application.

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Hi Crossbow,

Thank you for your reply. I got some more newbie question. We do not have the face mounted console thing. The battery is dead when it checked it. Is it safe to say that the program in the PLC is gone once the battery died out?

Correct me if I am wrong, but the difference between PLC and smart relay is that PLC can do arithmetic? Is it safe to say that if I do not have any analog inputs or outputs need, I can just use a smart relay instead of PLC?

Do you have other brands aside from Seimens that you can recommend that uses ladder? Something cheaper but gets the job done. I just need to get the relays, limit switches, and solenoid working together.

Are there any free software to program a PLC? Or we really need to buy the software from the company that made the PLC?

 

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With seeing the amount of I/O points on the old controller, a Micrologix 1100 could be a replacement, You can use the free version of RsLogix Micro starter lite to program it. 

Mike

 

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You do possibly have a lifeline that the program is stored on a eprom. If you remove the front cover the middle part on the front there maybe an eprom. 

Good luck

Rod Strick 

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