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14. Use with Galil Controllers

Integration with Galil Optima Series, DMC-18x2 and DMC-21x2/3 industrial motion controllers.

Version 2.1 of the BFF Motion Driver introduces support for Galil Optima Series, DMC-18x2, and DMC-21x2/3 motion controllers. These are high specification industrial motion controllers and can be used for controlling multiple channel servo systems.

The control scheme adopted utilises the Position Tracking (PT) motion mode of the above Galil controllers. In this mode the DMC controller is programmed to follow on-the-fly position demands sent from the Motion Driver to the controller through the DMCwin32 Galil Windows API. In this motion mode the DMC controller handles all the closed loop servo processing and the scheme can result in high fidelity motion response to the motion cues exported by the motion driver. It will be of particular interest to commercial platform builders.

To implement the scheme a DMC code control program must be written for the controller. This program is held in a text file and is loaded into the controller by the motion driver and executed by the driver at run time under operator instruction. The DMC program will include the core commands which put the controller into PT mode and which instruct the controller to read the position demands sent from the driver and use them as its position targets. The program will also include appropriate startup encoder calibration, motion parameter settings such as maximum speeds and accelerations and PID gain settings and platform parking and error handling functions.

An example of the DMC program is shown below. Please consult the Galil controller and DMC programming manuals for full details of the controller programming facilities. You will need to write the program to suit you particular drive system and performance requirements. Comments in blue are explanatory and would not be included in the program.

Contents of BFFP1.dmc text file -

#BFFP1                Program start label – must be as shown

KP5,5,5                 PID gains – values illustrative

KI0.005,0.005,0.005

KD0.8,0.8,0.8

DP-1080,-1080,-1080                  Set absolute position – known when physically parked – values illustrative

FL1000,1000,1000                  Set travel limits – values illustrative

BL-1000,-1000,-1000

SP200,200,200                  Set slow speed – all values illustrative

AC67107840,67107840,67107840                  Set acceleration (high for PT mode)

DC67107840,67107840,67107840                  Set deceleration

SH

PA0,0,0                  Send to start/hold position

BG                  Begin motion

pos1=0                  Set initial PT mode position demands

pos2=0                  pos1, pos2 and pos3 are the internal variables that hold the current position demands

pos3=0                  these are updated by the motion driver in real-time

park=0                  Set park instruction variable to 0

WT10000                  Wait for the platform to settle at hold position

SP30000,30000,30000                  Set PT mode working max speed

PT1,1,1                  Initiate PT mode in each channel

#LOOP                  Start of PT mode internal loop

PApos1,pos2,pos3        Set pos1, pos2 and pos3 as the current position targets (updated in the background) by the motion driver

IF(park=1)                  Goto #PRK subroutine if park variables goes to 1

JP#PRK                  Jump to #PRK subroutine

ENDIF

WT10                  Wait 10ms

JP#LOOP                  Go back to start of PT loop

#PRK                  #PRK Park subroutine

ST

SP200,200,200                  Set slow speed

PA-1080,-1080,-1080                  Go to park position

BG

AM

WT4000

ST

MO                  shut down motors

EN                  End
 

Use of #BFFP1 and #PRK program labels is mandatory, as is the use of the variables pos1, pos2, pos3 and park to hold the position demands and parking instruction.

Communication with the motion driver requires only that the DMC controller has been “registered” on the host PC using the Galil software provided for the controller. The communications mechanism is either TCP/IP or UDP or by RS232 Serial comms and is specified using the Galil software provided for use with the controller. Once so registered the motion driver can communicate with the controller regardless of the connection mechanism implemented.

Operation

The DMC control program must be saved in a “BFFP1.dmc” file in the motion driver's working directory.

The data output mode of the motion driver should be set to Mode=GAL in the .bff configuration file. The working range of the actuators and start/hold positions should also be set in the .bff configuration file in encoder quadrature counts AS USED BY THE DMC CONTROLLER.

Ensure that a copy of the DMCwin32.dll is installed on the host PC. This should automatically be the case if the Galil controller software has previously been installed and the controller has been registered on the PC.

On Driver startup the user will be prompted to confirm loading and execution of the #BFFP1 DMC program to the controller. If programmed appropriately the controller will go through the programmed startup calibration and slow travel to start/hold position routine and then enter Position Tracking mode. On confirmation from the operator the motion driver will then commence exporting motion cue position demands to the controller.

On driver shut-down the operator will be prompted to confirm execution of the #PRK parking subroutine in the DMC program which will take the controller out of PT mode and send it at slow speed to its park position.

NOTE Please consult the Galil documentation for your controller to establish a suitable DMC program for your system. The above program is illustrative.

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