[stump1189]

Is a plc ladder an actual program stored in the machine or is it just the machine parameters? From researching I know it has I/O's that control different relays, etc.
At first I thought it was a program file stored in the machine. I told a guy I needed the ladder for a hitachi seiki ht15 lathe and he emailed me a parameter list...I was expecting a file. Lol it sucks when your confused.....

[Al_The_Man]

The web can enlighten you a bit more as to the nature of it.
But essentially it is the Machine (M,S,T code) control logic file, it is a boolean representation of what originally used to be external hard wiring to control the machine I/O, as some early CNC were wired this way.
Depending on what make of CNC controller you have will depend on how it is implemented.
In the early days, when machines went to PLC from hard wiring, the PLC was an external unit that could be implemented by virtually any third party supplier, now most CNC have their own co-processor that works hand in hand with the CNC (motion) controller and each pass info back and forth to each other.
The bottom line is, it is often a separate file that has to be loaded with a specialized PLC file loader.
If yours H.S. is an older Fanuc it is usually done this way, Mitsubishi can be loaded from RS232 etc, or edited on screen.
Does yours have the Seicos Control?
Al.

[stump1189]

Thanks Al,
I think it's an actual file. There has been older post on this forum about uploading the ladder with yu yu software. If it was just parameters you cold do it all by hand.

[stump1189]

Sorry Al
I didn't answer your question.....yes it has Seicos M16 2 control. Lathe sat up for 2 years . That means plc battery dead, no plc ladder backp file.

[Al_The_Man]

Your only chance is to hope someone has the same machine and send a copy.
I did some on screen changes many years ago on a Seicos, at that time there was support from H.S. but I have since lost the info on it.
Al.

[stump1189]

It's hard to believe that one little C cell battery renders an entire machine useless......no wonder Hitachi Seiki went out of business.

[jasminder]

Your only chance is to hope someone has the same machine and send a copy.
I did some on screen changes many years ago on a Seicos, at that time there was support from H.S. but I have since lost the info on it.
Al.

dear Al,
i met a machine like that (same made with same control) a year before. It was saying "PC not ready" all the time. The battery was not holding enough charge when i measured with a Multimeter and replaced with a new one. I don't know what happened to the machine after that.

I am curious to know what do the retrofitters do to such machines? do they just put new controls on them while keeping the older servos and electronics or they do understand how the parameters work and write their own (as you said they are boolean expressions, i believe it will be hard to configure without the manuals or literature in case the machine does not have it).
I have a friend who got 2 okuma lb15 lathes but both have no parameters. I advised him to put a PC based (Mach3) control on them but the things got stuck with the analogue servo drives on the lathe with not any input for step/dir signals. So i have a question in my mind about what "they" do with such controls?

Btw i admire your memory, because you already knew that there is a seicos on the hitachi seiki ht15 that guy is talking about. Make me your disciple man!

jasminder singh

[jasminder]

It's hard to believe that one little C cell battery renders an entire machine useless......no wonder Hitachi Seiki went out of business.

dear friend,
i just talked to a guy from Fagor cnc controls and was surprised and glad to know that some cnc controls are available in the market that do not require any backup batteries these days. I am surprised why it took so long for the developers to make such things.

jasminder singh

[Al_The_Man]

I am curious to know what do the retrofitters do to such machines? do they just put new controls on them while keeping the older servos and or they do understand how the parameters work and write their own (as you said they are boolean expressions, i believe it will be hard to configure without the manuals or literature in case the machine does not have it).
So i have a question in my mind about what "they" do with such controls?

J.S. The older machines with analogue control usually have DC brushed motors and by now they will be getting towards the end of their life, there are not many controls that will allow mix and matching of 3rd party motor/drives anymore, older Fanucs, Fagor and a couple of others used to allow this.
If the machine is still in good mechanical shape or it is a very large machine where the replacement is many $$$ then it is economically feasible to put on a complete system.
I started with Fanuc, but went over to Mitsubishi, just because of the support etc.
The ladder is rewritten according to the machine requirements.
Mitsubishi have special PLC routines for auto tool changers which are often tricky to implement.
Al.

[stump1189]

Hi Jasminder,
The guy who emailed me the parameters use to have HT-15 lathe he said when the plc battery dies it deletes the memory from the machine. He said the ladder just tells you what the machine is doing. The machine is in storage now, the guy who I bought it from said when you powered it up it was getting an error on the screen (he doesn't remember what the error was) but he said you couldn't get to the para screen and the hyraulics wouldn't power up. I can't figure out whether the ladder is para or a file....if it's para I would bring it to shop to invesigate more.....if ladder is file I'm parting it out.

[Al_The_Man]

The ladder is not simple parameters. To plug it in by hand you would need to know the correct logic commands, even if you have a hard copy.
This is the sort of thing you see in the ladder screen when it is present and you pull it up.
Normally there is a hard copy print out with a machine.
ladder diagram_Automation-Drive
It is used as a diagnostic tool also if you have problems on the machine control side.
Al.

[stump1189]

Al,
I should assume that the ladder is gone correct?
From what I have read about PLC's once the battery fails everything is toast.

[Al_The_Man]

It has been too long for me to remember how to pull it up, if you got the manuals, it should describe how to pull the ladder screen up, and see if there is anything on it.
But IIRC if the battery goes, you lose the ladder.
Al.

[stump1189]

Hi Al,
I just put up a post for HT-15 ladder...maybe i'll get lucky.
Thanks for the help.

[jasminder]

Normally there is a hard copy print out with a machine.
ladder diagram_Automation-Drive
Al.

Hmm,
the things seems really complicated there. I think i should stick to the Mach3 and the step/dir things only. these parameters and ladders are out of my understanding. BTW do the latest controls from siemens and fanuc also need the ladders?

jasminder

[Al_The_Man]

Practically all commercial CNC uses a PLC or a controller for the machine control side, the CNC side dedicates its time to servo or motion control, it passes the part program request for M.S.T and all other functions over to the PLC side.

Ladder is just a way of displaying the Boolean mnemonics in a way that makes it very much easier to trouble shoot control problems in a visual manner, as it represents the old hard wired way of schematic drawings.

A control such as Mach where the loop is not closed by the actual controller does not have the problem of simultaneous functions such as CNC motion AND M.S,T control as it passes the CNC motion responsibility over to the drives.
Al.

[Al_The_Man]

Hi Al,
I just put up a post for HT-15 ladder...maybe i'll get lucky.
Thanks for the help.

Stump, try contacting Hitachi_Man here on the forum, he is a H.S. Tech.
Al.