Model 789A-3
Digital Scan Control and Motor Driver
- Selectable Speeds 0.1 to 99 nm/min (local mode)
- Selectable baud rates: 300, 1200, 2400, 4800, 9600, 19.2K, and 39K (Factory set to 9600)
- Hi and Low Limit Switch Interlocks
- Slew function permits high speed 'go to'
- LEDs provide status Information at a glance
- RS232 communications standard, IEEE available
- LED digital display available
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The Model 789A-3 scan controller provides the user with a low cost, high resolution, easy to use, stepper motor scanning system. The Model 789A-3 comes complete with a stepping motor to fit McPherson monochromators and/or sample handling accessories. The cabling for power and limit switches, controller, and power supply are furnished with this controller. Selectable features include scanning direction, rate, and motor enable/disable. Indicate the model number of the instrument to be fitted if not ordering with the instrument.
The Model 789A-3 is used for instrument upgrade and reconditioning too. The Model 789A-3 digital scan control is an essential part of most upgrades. Once installed it allows wavelength control and facilitates data acquisition via computer.
User friendly front panel controls selection of all functions. Our standard serial interface (RS232) permits selectable features to be changed remotely. No analog to digital or I/O boards required. For users interested in controlling devices via TTL or C-MOS logic, consult factory for details.
PDF format Data Sheet for the 789A-3 scan control available here
Specifications
McPherson Model 789A-3 Digital Scan Control
| Power | 100 - 240 VAC, 50/60 Hz, 20 Watts |
| Motor Resolution | 36,000 step/rev, up to 50,000 step/rev available |
| Motor | 24 volts @ 1.0 amp/phase (NEMA 23) (Consult factory for other available motors.) |
| Physical Dimensions | Width: 8.38" (213-mm) x Height: 5.22" (13-mm) x Depth: 14?3/8" (365-mm) |
| Weight | 8.75 lbs (3.98 Kg) |
Programming Command Set Summary
Command Set / Programming the Model 789A-3 via RS-232
| Command | Description | | Command | Description |
| ESC | ABORT/TERMINATE | | S | RELATIVE INDEX |
| @ | SOFT STOP | | S | STORE PARAMETERS AS DEFAULTS |
| ^C | RESET* | | T | TRIP POINT SET |
| B | JOG SEEDS SLOW FAST | | + | + STEP COMMAND |
| C | RESTORE/INITIALIZE | | - | - STEP COMMAND |
| F | FIND HOME | | V | SLEW VELOCITY |
| G | GO FROM ADDRESS/TRACE*** | | W | WAIT IN MILLISECONDS |
| I | INITIAL VELOCITY | | X | EXAMINE PARAMETERS |
| J | JUMP TO ADDRESS | | Z | DISPLAY POSITION |
| K | RAMP SLOPE | | [ | READ NON-VOLATILE MEMORY |
| L | LOOP ON PORT*** | | \ | WRITE TO NON-VOLATILE MEMORY |
| M | MOVE AT CONSTANT SPEED* | | ] | QUERY HARDWARE STATUS |
| O | ORIGIN SET | | ^ | QUERY MOTION |
| P | PROGRAM*** | | _ | PROFILE |
| Q | QUERY (list) PROGRAM*** |
* all daisy chained devices respond
** Continuous Motion (distance not set)
*** For Internal Program Only (see sample program below)
Programming Example
Objective: To scan the instrument at a rate of 10 Å/Min. over a range of 5 Å. After completion of the scan, change direction and slew back to the starting wavelength at a rate of 2000 Å/Min. Motor resolution is set to 36000 steps/rev.
| P84 (CR) | |
| 84 V60 | 60 steps/sec (1 0 Å/min) |
| 87+ 1800 | 5 Å wavelength range (1800 steps) |
| 93 W1 | Wait 1 millisecond to change velocity. |
| 96 V12000 | Change V to 12000 steps/sec. (2000 Å/Min.) |
| 98-1800 | Change direction & return 1800 steps. |
| 102 P (CR) | Stores program, exits to command mode. |
| Q84 (CR) | To verify or review program. |
| (CR) | To scroll through the program. |
| G84 (CR) | To run program. |
