Newport MM4000 Device Support for the Motor Record

Contents

• Overview
• Hardware Configuration
• Limitations
• vxWorks Startup Script
• Files

The Newport MM4000 and MM4005 (referred together as MM4000 in this document) are intelligent motor controllers which can control 4 (MM4000) or 8 (MM4005) motors. They can control any mix of stepping motors and DC motors, with encoders. The controllers have a front panel for user control and communicate to a host via IEEE-488 (GPIB) or RS-232.

This MM4000 device package is written to provide full implementation of the features of the motor record. The VME crate communicates with the MM4000 either via GPIB (using any supported GPIB driver, e.g. National Instruments 1014 or Hideos GPIB) or via Hideos RS-232.

Hardware Configuration

The communications settings of the MM4000 must be configured using the front panel menus. If GPIB is selected then the device address (range 1-31) must be entered. This device address must agree with that specified in the vxWorks startup script (see below). If RS-232 is selected then the baud rate, parity and stop bits and terminator must be selected. The baud rate, parity and stop bits must agree with those specified in the vxWorks startup script (see below). The terminator must be set to <CR> only.

It is important to set correctly the software limits of each motor using the front panel. If the software limits are correctly set then the motor will never hit a hardware limit. It is important to do this, because if a motor does hit a software limit the MM4000 turns off the motor power to all motors, which can be very annoying.

Limitations

• The backlash feature of the motor record does not presently work. This is due to the way the record implements backlash, which basically makes assumptions about the controller which are only valid for OMS. This problem will be fixed in a future release of the motor record. However, the MM4000 itself can be set up to do backlash correction using the front panel, and this correction will be done properly.

• The motor record wants to talk to the controller in "steps", while the MM4000 can only be programmed in "user units" (e.g. mm, inches, microns, degrees, etc.). The MM4000 device support works around this limitation as follows:
  In the initialization procedure the device support asks the MM4000 for the encoder resolution of each motor, which is the number of user units per encoder pulse. If the motor is a stepper without encoders this value is the size a single step. The device support uses the encoder resolution to convert all positions reported back to the motor record into encoder pulses. It converts all move commands from the motor record from encoder pulses into user units before sending them to the MM4000. The user units for each axis are selected using the front panel. It does not matter what units are selected - a translator can be in inches, microns or mm. The only limitation is that the user units must not be changed from the front panel after the IOC is booted.

• Absolute position.

• MM4000Setup(int numCards, int maxAxes)
  • numCards is the maximum number of MM4000 controllers to be used. The default value is 4 and the memory usage for unused controllers is very small.

  If the default values of both numCards is acceptable then MM4000Setup does not have to be called from the vxWorks startup script.

• MM4000Config(int controller, int portType, int addr1, int addr2)

  This function must be called for each MM4000 controller to configure it.

  • card is the number of the controller being configured, in the range 0 to numCards-1.

devMM4000.c contains the device support. These functions have knowledge of the motor record and of how to call the routines in drvMM4000.c They have no knowledge of the details of how the MM4000 works.

drvMM4000.c is true EPICS driver, with init() and report() functions. However, its init() function does not do the real initialization, since it needs the GPIB driver which may not have been intialized before the MM4000 init() function is called. Thus, the real initialization in drvMM4000 is done from a call from the device support init() routine, which is called after all drivers have been initialized.

These files can all be obtained in a compressed tar file. This file should be untarred in a <top>/xxxApp/ directory.