hydraulic motor lathe turret, keep switches or switch to rotary encoder ?

So I have a turret style lathe, it has 6 positions, and ID and OD tools. so 12 tools on 6 stops. The current configuration is 4 contact switches, and 2 for turret lock/unlock. It also has a hydraulic motor that turns a ring and pinion gear arrangement, the control of the hydraulic motor looks to mostly be getting the PLC correct. Flip on the relay, feed oil, spin turret. is it better to put a  300ppr " as an example" rotary encoder on the turret or stick with the 4 switch configuration, which one would be more robust in terms of accurately figuring out where the turret is in it's rotation ? the encoder would also have the advantage of a Index point. 

Has anyone done either configuration and if so what are the pro's and cons of each, I did some googling and I didn't come up with much. 

I would stick to the current setup and use the carousel component. Your setup most likely produce a BCD code on the 4 switches 

Type man carousel in a terminal 

 

The 4 switches used to run to a card in the arcamatic io rack. They do produce a 16 combination array for position, i could wire them up to 4 inputs, 

The machine uses hydraulics everywhere, tailstock, chuck, way lube etc. It has a dedicated 7.5hp hydraulic pump with cooling system.

I do have the switch array info however.

I'm not to the point of being ready just yet but shortly. There is some concern of other parts of the machine, namely resolvers being compatible with the 7i49 board. So i may wind up doing a heavy retrofit depending on what the outcome of the resolver situation is.

I do concur that a servi might be more practical and I also have a few spare encoders and large steppers around.

The resolvers connected to the IO rack and communicated on a serial bus of unknown design to the servo control cards.

I did find information about similar resolvers.

I think however that given the age of the resolvers and the questionable specifications, I'm probably going to just dump them and install encoders.

It'll certainly get the machine up and running much faster.

In intend to stick with the Acramatic drives, the Z servo is 7.5hp and the x is 5hp, these are not trivially sized drives  the spindle servo is 30hp.All are DC drives. The resolvers themselves are on geared couplings attached to the lead screws and the spindle itself with a takeoff belt on a standalone housing.. I am not particularly worried about the physical conversion aspect of the resolvers nor really the electrical conversion. 

She's a big powerful machine

the resolver datasheet state Ratio of 0.5, and it is a 5v resolver, but since it's just a coil of wire, I don't see whay the exact voltage would matter a whole lot, but the turns ratio certainly would. 

Here's a link to the datasheet, tell me what you think,I removed the actual resolver and I have it in hand,  to my brain these seem like they should work with a 7i49. Also these resolvers are on 2:1 stepup gear boxs to increase resolution. 

www.mouser.com/datasheet/2/28/11BRW-300-M10B-958150.pdf