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Revision as of 15:24, 19 April 2011 by Hovanes (Talk | contribs) (Motor Applications Introduction)

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General


EPICS on Linux


Motor Applications Introduction

We need to plan for the following motor-based applications:

  • Goniometer (5 axis)
  • Tagger harp (1 axis)
  • Tagger microscope (4 axis)
  • Collimator table (1 axis)
  • Converter/photon harp (1 axis)
  • TAC (1 axis) ?
  • Gamma profiler (1 axis) ?

This means 10 axes in tagger hall, 4 axes in Hall D. We can consider the three options shown below.


VME based

  • This approach would require two VME crate with a controller in each (one in tagger hall and one in Hall D) and OMS motor driver cards. This is a common way of doing it at Jefferson Lab.
  • Currently we are trying to avoid VME based systems, but harp applications need to have a VME scaler module. Therefore, for harp systems this would be a convenient way of doing it since the motor and the scaler module can be easily synchronized through a single VME bus.
  • The hardware cost can be high ~ $???? for the two VME crates, CPUs and the 4 OMS cards.
  • Software from other halls and accelerator division can be used saving us on labor cost.



PLC based

  • PLC may be the cheapest way of doing it. For 18 axes of motion we probably will need about $16K; $14K for 9 AMCI 3202 modules for 1756, and approximately $2K for a 1756 chassis with a communication module.
  • We will need to develop the software nearly from scratch.
  • Implementing harp scans can be problematic because of the synchronization issue between the scalers and the motor read-backs.


Newport XPS based

  • A new module for controlling multiple motor drivers from Newport with Newport XPS-DRV00 pass-through cards can be used.
  • This approached apparently is not used in JLab.
  • Mark Rivers uses these devices at APS and he developed EPICS support for this. In fact his SNL applications is probably directly usable for us, so little software development would be needed for this. He is using the pulse output from XPS to strobe the scaler module, and keeps the positions of the motors (encoders) in XPS to later synchronize with the scaler FIFO values. This is exactly what we are looking for.
  • Mark Rivers is working on changing this application to work without state code, which he briefly described in an e-mail exchange.
  • The low-power motors can be controlled using XPS-DRV01 card, which is more expensive that pass-through cards, $571.00. But this would allow us skip the creating driver box for applications like microscope counter and LED positioning.
  • This is an expensive option. The price for 3 XPS-C6 units fully equipped with six XPS-DRV00 cards would cost us $23K.
  • Software development cost is probably going to be low since we can nearly copy APS' application.


Goniometer Application

No plans now


Tagger Harp

Tagger harp mechanical hardware is within the accelerator group's scope. They will installed the vacuum system and the motor, but we probably will have to instrument the harp stick and decide what readout we will need. In order to achieve 10^{{4}} dynamic range we need to instrument it with PMT-based readout, which accelerator division usually does not do.

PLC