Allen Bradley 1771

[macgeek10]

Hey guys i'm new to the cnc scene, but i have a really good parts connection. He has already gotten me a whole slew of allen bradley parts they were throwing away at his factory. they all work too .

Here's the list:

Cat 1785-l30b
Key switch, parrall port, input
Plc-530c processor module


Cat 1771-0bd
10-60 volt dc motor output


1771-sdnb
Device net scanner module


1771-sim
8 pt desecret io


1771 – p4s
120 vt ac volt power supply module


Box
1771a1b
4 slot io chassy


2 encoders

842d-60131331bda
842d-60131331bxa


Allen bradly Message view 421 f


I have no idea what to do with this stuff, but I know its for extreme factory automation and stuff like that. I want to know how to control a 3 axis cnc machine with it. servos, steppers, i'm not sure, like i said, i'm new to this.

Any help or advice would be greatly appreciated, i'm sure some of you guys would have a field day with this stuff, so help me out as best as you can.

Thanks
john

[Al_The_Man]

A-B 1771 is a very old PLC version, it is not much use for CNC apart from using as an out board PLC functions, there were motor motion modules but interpolated moves are not possible.
The later, more compact SLC 500 is more popular, but still a PLC.
Al.

[macgeek10]

Ok ok ok, wait up. Why not a plc? I can get this stuff for free, and i really don't want to have to drop a bunch of money to make a simple pcb router.

[Al_The_Man]

Originally Posted by macgeek10 Ok ok ok, wait up. Why not a plc? I can get this stuff for free, .

Just because its free doesn't mean it will work .
A PLC is intended for general logic control and was original purpose was to replace hardwired relay machine control logic, for which it still fits that purpose, overtime specialty modules have been added, but so far there is a distinction between the CNC processor, which attempts operate in 'real time' and the general machine control, which is handled by the PLC.
The CNC processor operates the motion control servo's, and devotes all its processing power to create the necessary interpolation of the axis.
The PLC handles the mundane tasks of turning on spindles, coolant pumps, tool changers etc.
If you just want a point to point machine, then it can be done with a PLC, but I can tell you now, if you have to buy the servo module for the 1771, the cost would be astronomical. (I think the OBD may be one, I would have to check).
Then you need very expensive software (If available). and the ability to write the control program.
Al.

[Al_The_Man]

Originally Posted by Al_The_Man . (I think the OBD may be one, I would have to check). .

Unfortunately is does not seem you even have a servo module as the OBD is a common DC ouput card, the servo positioning card is the QC module.
I once took a 1 week AB course on just how to integrate the QC card. ( it is not for the faint of heart).
There are cheaper ways.
Al.

[macgeek10]

Ok thanks it looks like i have a bunch of very very expensive unsellable paperweights, but i could tinker some with them later. Can i use the encoders though, I think they are used for high precision stuff, and i am going to be making pcbs.

[Al_The_Man]

[QUOTE=macgeek10. Can i use the encoders though, I think they are used for high precision stuff, .[/QUOTE]
Encoders always come in handy, you may find a buyer on ebay but the 1771 series can be picked up for peanuts now, due to its age.
Al.

[veeguy]

THe stuff you have is for the PLC-5 series PLCs. It is one of the largest installed base families of PLC around. They are still currently made and sold. That said, they won't do what you want.

I suppose you could get a CPU for your 4 slot rack, and a power supply. THen get the RSLogix software (about $3000) and use a DC output card to output step and direction commands to a stepper driver controlled board router or mill. It would take LOADS of ladder programming, and would be totally ungainly. What you would be doing is replacing a $300.- PC with a $8000.- PLC (but you still need the PC to program the PLC...) sooooo...

Best idea--- Sell the AB stuff on ebay, take the cash and buy a HobbyCNC board kit with their motor package and do it right! You should even have some cash left over to buy some of the mechanical stuff you will need.

[macgeek10]

Some of the stuff I have is proprietary, with no model numbers on it at all, and some of it says PROTOTYPE on it. I can't sell this stuff, so I pretty much have a bunch of really heavy, really expensive, paperweights. SIGHHH. Oh well, I got ahold of my middle school tech ed teacher, and I am going to machine out my own stepper control boards. Thanks for your help guys, I am pretty much making a learning experience out of all of this. I guess I could always use the PLC's to make some simple light stuff or something, or just pitch the crap, that's what AB was going to do with it.