Online Programming Capability

What is online programming capability?

Some PLC you can not change the program online (you have to make the change then down load)....others support that feature

oh, so if I have a customer looking for a PLC with online programming capability, it doesn't mean they need the software as well, just simply the plc capable of programming online?

For instance, I'm kind of stuck on this topic,

Method of Control: PLC with online programming capability for interface to the starters / drives. Wireless communication is to be provided between crane control system and mill DCS system.

I interpret this as hardware without a great deal of further info.

The software is required for programming the PLC, regardless of if it can be done online or offline.

Rick

Casey said:

Method of Control: PLC with online programming capability for interface to the starters / drives. Wireless communication is to be provided between crane control system and mill DCS system.

I interpret this as hardware without a great deal of further info.

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I interpret as, PLC with online programming capability....and Wireless communication...and the ability to communicate with the DCS

You need to see what the protocol is with the DCS as well, if this is a potential customer then I would ask for more detail...or go there and dig...also what Rick has stated..

I do not know what you require. I normally use Omron and they have full online programming facilities available. My understaing is that AB Control Logix has a memory area where you can do your changes, test them and then flick the changes into the system. Siemens goes offline and you have to download the changes. A client of mine advised me to break Siemens programs into small pieces in FBs to facilitate this.

Much more detail required.

Method of Control: PLC with online programming capability for interface to the starters / drives.

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It does not mean that you have to deliver any means of programming, only that the PLC must be online programmable.

Wireless communication is to be provided between crane control system and mill DCS system.

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Uh-oh. You must definitely dig into this a bit further. What is the DCS system, and what kind of protocols are supported ?
It more or less indicate that you must have some kind of ethernet connection to the PLC. There a wireless connection methods that are not ethernet, but they are less common.

Siemens goes offline and you have to download the changes. A client of mine advised me to break Siemens programs into small pieces in FBs to facilitate this.

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The words "online programming" means to me that you can modify the software without having to shutdown or stop the system. Siemens S7 lets you do this. The use of FBs has nothing to do with this. FBs are used when you make reusable code.

Far as I understand on line edits there is 4 ways.

Modicon way:in this way whayt you type on your screen is what you get on the PLC,at the next scan the instruction is excute.

Omron way:In that way you edit some rungs when you done it go in but the outputs and inputs are freezing they status.
Since you edit some rungs the period of freezing is short.

A-B:You can edit what ever you want when you test the edits its replace the old file at the beginning of the scan.so it should not any interfering to the scan.

Koyo and other:They allow to download whill the PLC is running but the outputs and inputs are freezing for a period, depend on the length of the code.

ArikBY said:

A-B:You can edit what ever you want when you test the edits its replace the old file at the beginning of the scan.so it should not any interfering to the scan...

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ArikBY,
It also depends on the model of AB, some you can others you cant

You are right

I meant to what can be edit online