Will, Today Barry and I empirically determined the polarity of the various I/O bits on the APF Galil controller that are associated with the science shutter that is controlled by the Uniblitz shutter controller. This shutter has an IR emitter/sensor that can be used to determine whether the shutter is open or not open. However, the IR sensor only returns a useful result if the IR emitter is enabled, and if the emitter is enabled, it spews stray light at the back of the spectrometer's slit. Hence, we plan to enable the emitter and check the shutter status only for periodic diagnostic checks. During science exposures, the emitter will be kept off, so as to not pollute the spectrometer with stray light from the IR emitter. The IR emitter is mapped to Galil output bit 11, and the signal from the IR sensor is mapped to Galil input 9. The polarities are as follows: Output bit 11: CB11 turns the IR emitter on SB11 turns the IR emitter off If Output bit 11 is in the low state (i.e., CB11=the emitter is ON), then: Input bit 9 reads 0 if the shutter is not open Input bit 9 reads 1 if the shutter is open If Output bit 11 is in the high state (i.e., SB11=the emitter is OFF), then: Input bit 9 always reads 1, regardless of the actual shutter state The command to open or close the science shutter comes from the APF UCAM CCD controller, and not from the Galil controller. Also, there are a couple of LEDs on the front panel of the Uniblitz controller (located in the APF Electronics rack) that provide useful information, as follows: The "Drive Active" LED is RED: This LED is OFF when the CCD controller is commanding the shutter to open This LED is ON when the CCD controller is commanding the shutter to close (NOTE: this LED doesn't indicate the actual state of shutter, but simply indicates the state to which the shutter is being commanded; if the shutter is stuck, its actual state may not match the commanded state.) The "Sync Active" LED is GREEN: This LED is OFF when Galil output bit 11 is high (SB11) and IR sensor is OFF This LED is ON when Galil output bit 11 is low (CB11) and IR sensor is ON The Uniblitz shutter controller can control up to 3 shutters. Currently: Shutter #1 = science shutter Shutter #2 = corner cube shutter Shutter #3 = unassigned The following new APFMOT keywords should be mapped to these Galil I/O bits SCISHSTA science_shutter_status read-only / ("open", "not open", "unknown") where: "open" = ((output bit 11 == 0) && (input bit 9 == 1)) "not open" = ((output bit 11 == 0) && (input bit 9 == 0)) "unknown" = ( output bit 11 == 1) SCISHIRE science_shutter_IR_sensor_enable_command read-write / ("enable", "disable") where: "enable" = ( output bit 11 == 0) "disable" = ( output bit 11 == 1) We have not yet determined the various polarities for the corner cube shutter, but will try to do so next week. CUBSHSTA cube_shutter_status read-only / ("open", "not open") where: "open" = TBD "not open" = TBD CUBSHCOM cube_shutter_command read-write / ("open", "close" ) where: "open" = TBD "close" = TBD Bob