ESI Spectrograph Electronics Manual
Overview:
The overview section of the manual contains an index of the schematics, a list of stages, and the general schematics for the Eshelette Spectrograph and Imager, ESI. It corresponds to the overview tab in the electronics schematics binder.
This document shows the various stage designations. The first column gives the stage ID that the software group uses. The second column is the name that the stage is known by. The third column gives the associated electronics schematic number and link. The forth column gives the controller number and the stage letter designation as known by the software. The fifth column gives the number of encoders used on that particular stage. The last column denotes how the stage moves. The possible types of movements are given in the note at the bottom of the page.
Overall Block Diagram, EL-3301
On the left-hand side of the page, a dashed box denotes the equipment that is located in the computer room. It shows the connection to the global Ethernet for both the Supervisory and Instrument computers. This is the public network within the observatory.
The Supervisory and Instrument Computers are connected to both the public network and also to a private network. The private network connects the Supervisory and Instrument Computers to a 'dumb' Cisco 100/10 Mbit/sec switch. Though these computers each have auto-detecting ports, they are both configured to run at 100 Mbit/sec. This reduces the possibility of problems where both the computer and the switch are auto-detecting and do not connect properly.
Among it's other tasks, the Supervisory Computer, a Sparc 5 machine, controls the various functions of the spectrograph such as moving filters, opening the hatch, and controlling calibration lamps, by sending commands to and receiving information from the Galil DMC-1580-72 Servo Motor Controllers. The Instrument Computer, a Sparc Ultra, is in charge of taking data functions. It connects to the CCD VME Crate via the Cisco switch and transmits and receives instructions, data, and status information.
As noted previously, the Cisco switch is used on a private network and connects to the computers at 100 Mbit/sec. The connection to the instrument is run at 10Mbit/sec due to the speed of the Lantronix ETS8UF Terminal Server and the CCD VME Crate. Because the computers are running at 100 Mbit/sec, the connections to the terminal server and the CCD VME Crate can run up to their full 10 Mbit/sec bandwidth.
The last piece of equipment in the left-hand box is the SCSI-to-Fiber converter. This box interfaces the duplex fiber connection of the Photometrics PXL TV Guide Camera signals into the control computer via a SCSI port.
The dashed box on the right-hand side of the page represents the equipment contained within the spectrograph. Starting at the top, as noted above, the Lantronix ETS8UF Terminal Server connects to the ESI private net. It can control up to 8 serial ports via RJ-45 jacks. Each of the two Galil controllers use two of the ports to communicate with the Supervisory Computer. It's main port takes care of the control and status functions and the auxiliary port, which is a transmit only port, is used exclusively for diagnostic output from the Galil controllers.
Each Galil controllers are stand-alone RS-232 units capable of generating output waveforms for up to eight axes. They also provide the necessary I/O for forward, reverse, and home limit switches. The controller ca be connected to up to two AMP-1400 power amplifier via four ribbon cables. The AMP-1400's provide the required power to run the servo motor stages. It also provides convenient terminal strips that break out the other signals from the controller. We have added a 'top hat' panel to each of the amplifiers to provide connections to the various motion stages via Amp CPC connectors. Lastly, it provides a place to mount our 24-channel analog input board. With this set-up, we have been able to make each stage connector and cable pin compatible. The -72 in the DMC-1580-72 refers to an additional 72 bits of I/O. These bits are used for various input and output functions such as turning on and off lamps etc.
In the middle of the right-hand box is the CCD Controller Box. This box contains the SDSU2 type controller boards. It talks to the CCD VME Crate via a duplex fiber optic cable. It works in tandem with the ESI Instrument computer to control and readout the CCD.
At the bottom of the right-hand box is the Photometrics PXL TV Guide Camera. It contains an AIA interface card that talks to the Photometrics AIA-To-SCSI (A2S) converter box. The A2S box in turn talks to the Black Box SCSI-to-Fiber converter that talks to a duplicate box in the computer room. Information from the camera is then sent to the appropriate computer to provide guiding functions.
Servo Stage Control Overall Block Diagram, EL-3302
The Servo Stage Control Overall Block Diagram consists of 6 sheets. Remember to use the vertical scroll bar on your Adobe Acrobat(TM) viewer to scroll between pages.
Sheet 1
Servo Stage Control Sheet 1
At the top of the drawing is the Lantronix terminal server. It connects to the ESI private network via a thinnet coax cable. The drawing shows two connections to each of the two Galil panels. In each case, one connection is made to the main port for control and status information and the other to the auxiliary port for diagnostic feed back. This leaves four ports available for future expansion. The connections are made with common RJ-45 connectors and cables. EL-1265 shows the wiring details.
The rest of the drawing shows the connections to the Galil controllers and amplifiers. Most of this discussion pertains to both panels but I will note any differences.
Each controller connects to three different Opto-22(TM) I/O mounting rack via the J101, J102, and J103 connectors. The cables for these connections are 50-conductor ribbon cables. The signals passed through these cables are individual digital I/O bits. The input and output bits are determined by configuring the software. I/O Modules are inserted in the proper slots as shown on the EL-3335 through EL-3340 (click Here for an example). The functions that the I/O modules control will be outlined in the Signals section.
The power to drive the servomotors comes from the Lambda LSR-56 power supply. It supplies 28 volts at about 23 amperes. This is enough power to run all eight possible channels at once. The AMP-1140 amplifiers receive analog signals from the controller and amplifies the power to the needed level to drive the stage motors.
Also connected to both the Opto-22(TM) boards and the AMP-1140 boards is a Power General SM3-25-1DCM triple power supply. It supplies the required voltages for limit switches, the Opto-22 boards, and the 24 Channel Analog Input Board. The +5 supply and its grounds are connected to the long terminal strips of each of the panels.
The bottom middle section of the sheet shows how each of the servo stages are connected to the Galil controller. Stages with secondary encoders have two cable connections shown i.e. the slit mask stage has a J1 and a J21.
Sheet 2
Servo Stage Control Sheet 2
This sheet shows the layout and internal connections of electronics locker #1. The input AC power cable connects to the EL-3304 AC power controller via a normal 4 inch square junction box. The wiring in the junction box connects the 'clean' power to the AC power controller and a second cable that goes electronics locker #2. The 'dirty' power is used to power the AC convenience outlets and is also sent to locker #2. The 'clean' power for this locker is connected to the input connector, JP1, of the AC power controller. The output of the controller is wired into the AC power strip and to the 'clean' convenience outlets. The 'clean' power convenience outlets should only be used for test equipment such as an oscilloscope and the like. Never use the 'clean' outlet for 'noisy' equipment such as drill motors and the like. This power is what runs the CCD and TV camera controllers and should be as free as possible from noise sources.
The other connections shown in this drawing are the AC plug to the Ion Pump Controller and two plugs for Galil Panel #0. The two for the Galil panel are: 1, the Galil box itself and 2, the plug for everything else on the panel. Note that the AC for the cooling fans comes from the Opto-22 panel #1.
Electronics locker #1 has been left sparsely populated so that it might be able to hold any future equipment associated with upgrades to the spectrograph.
The EL-3304 box is used to shutdown the power to the locker if the temperature get too high. See the section on Temperature Monitoring below.
Sheet 3
Servo Stage Control Sheet 3
This sheet is similar to sheet two. The input AC wiring is handled the same way as locker #1 except that we don't provide a 'clean' power convenience outlet and we only send the 'clean' power to box two.
This box contains the second Galil controller, the Lantronix terminal server, and the calibration and continuum lamps. Galil panel #1 in this box only drives four stages and thus only has one of the AMP-1140 amplifiers connected to it. The cooling fans are again controlled via Galil output bits.
The Lantronix box is mounted on the bottom plate next to the cooling fans. It is mounted with it's indicator lights pointing out from the locker. This makes it easier for troubleshooting but unfortunately, it makes it harder to plug into the port connectors. If you need to connect cables to the box it will be easier to either use an inspection mirror and flashlight or to take the box out of it's mounting strap. To take the box off, loosen the screw on the left-hand side of the box and then remove the screw from the side of the bracket next to the cooling fans. The RJ-45 connectors can now be accessed by flipping the box over.
The schematic for the lamp control is EL-3368, below is a diagram of the lamp box. The calibration lamps are mounted inside a cylinder that is mounted outside of and above the locker. The lamps that we are using are Pen-Ray neon and argon, a Photron copper-argon, and an Osram quartz lamp. The Pen-Rays use Pen-Ray PS-3 power supplies. The manual switch is left in the on position and the Galil controls the AC to each of them. I/O bit 33 controls the neon lamp and bit 34 controls the argon lamp.
The copper-argon lamp is turned off and on by I/O bit 32. When the power is turned on, the four hundred volt output of the power supply is applied to the EL-1262 control circuit that is mounted in a blue case on the side of the locker. This circuit sets and maintains the lamp current at the required 5 milliamperes. The regulated current output of this circuit is then applied to the lamp.
The quartz lamp is powered 15V power supply with a __ ohm resistor in series. When I/O bit 35 is set, AC is applied to the supply and 15V is applied to the lamp.
Calibration Lamp Box
The drawing above shows the lamp layout in the calibration lamp box. The copper-argon hollow cathode is mounted co-linear with the fiber optic bundle. Coming in from the side are a quartz lamp, two each neon, and argon lamps. If at some time in the future the need for different or more of these lamps arises, the I/O module output can be used to control multiple power supplies or new bits/modules can be assigned.
Sheet 4
Servo Stage Control Sheet 4
This sheet shows the contents and wiring of electronics locker #2. In this case, the only AC power that comes into the locker is the 'clean' power. It comes into a junction box and then is wired to the multiple outlet strip. This locker doesn't contain a Galil controller so the cooling fans are handled differently. The Utility Board in the CCD controller sets and clears Dout 14 to send a TTL level signal the EL-3316 Fan Controller. This box contains a Crydom D1225 solid state relay that controls the power to the cooling fans.
The CCD Controller takes up most of the room in the locker but also squeezed in are the dewar shutter control box, the Photometrics TV camera controller, an AIA-to-SCSI converter, and a SCSI-to-Fiber converter.
Sheet 5
Servo Stage Control Sheet 5
This sheet shows the air operated hatch stage and the CCD shutter. The hatch is opened by toggling bit 27 and closed by toggling bit 28 on the second controller, number 1. The state of the hatch is monitored on bits 93 and 94 of the same controller. Bit 93 is asserted (low) when the hatch is open and bit 94 is asserted when the hatch is closed.
The CCD shutter is controlled via a designated bit on the SDSU2 Utility Board. Setting the bit high opens the shutter and setting it low closes it. The Shutter Controller, EL-1183, translates the binary state of the shutter control bit into pulses that are sent to the actual shutter. This shutter has two blades that we will refer to as left and right. When the AC power comes up on the shutter controller, it moves the right blade to the out position and then moves the left blade in if it is not there already. When the controller receives a signal to open the shutter it opens the left blade. When it is told to close the shutter it will close the right blade this time. On successive operations, the controller moves alternate blades in and out. This pattern of right-out-right-in-left-out-left-in helps insure that the CCD is illuminated evenly during an exposure.
The drawing also shows the low air pressure switch that is monitor on bit 89 of Opto-22 panel #6. The drawing does not include pneumatic equipment such as regulators, dryers, and valves. Please refer to the Keck purge panel drawing.
Sheet 6
Servo Stage Control Sheet 6
This sheet shows the overall view of the various inputs and outputs that control stages other then the servo motor stages. Starting on the left-hand side are the cooling fans for electronics locker one (controller #0). These fans circulate the air in the locker across the coils of a heat exchanger under the local control of the Galil controller. Bit 30, I/O module 5, turn the fans on and off. The same scheme is used on the second Galil controller in locker three (controller #1). Beneath the fan box is the Photometrics PXL TV Camera control. The camera controller AC is turned on and off by setting and clearing bit 29 on controller #0. The Over Temperature Shutdown box is described in the section on the EL-3304. This diagram shows that bit 31 on each of the controllers can shutdown the power in it's own locker. This should only happen if temperature runs away and the Supervisory computer instructs the Galil to drop the power. Even so, if the temperature goes above 85° F a thermostat mounted on the Opto-22 relay rack mounting plate will drop the power relay. This is again repeated in locker #3.
Both lockers have connections for the EL-3385 manual paddle. The paddle is described in the Wiring Section
Sheet 7
Servo Stage Control Sheet 7
This drawing show the input AC control scheme in electronics lockers #1 and #3. The heavy-duty power relay is used to interrupt the 'clean' power if either the thermostat reaches 85 degrees or the Galil controller sends a signal to drop the power. The Galil would drop out the power if the temperature rises above ambient temperature plus five degrees centigrade or if it sensing the logic power voltage going out of spec. If either of these happen, pins 2 and 4 are shorted together providing a path for the AC current to energize the relay coil. This breaks the 'clean' AC power circuit and once broken it can only be restored by either pushing the reset button or by momentarily removing the power to the locker.
IMPORTANT: Electronics locker #1 works independently of the other lockers but locker #3 also controls power to locker #2. Locker #2 contains the CCD and TV controllers.
When power is dropped out a sonalert will sound until the power is reset. Remember though, these sonalerts are located on the external wall of the electronics lockers and may not be heard unless you are near the instrument. Also, note that the 'dirty' power is passed through the control box but is not interrupted by it.
Sheet 8
Servo Stage Control Sheet 8
(Also refer to drawing EL-3332 for the wiring of the terminal blocks.)
This sheet shows how the various power supplies and grounds are run on each of the Galil panel. Heavy ground wires are connected to a screw in the panel itself. The green lines on the drawing show these ground wires. By tying the grounds together at only one place we help to eliminate ground loops. The logic supply is wired to the terminal strips. The ground is tied to one set of terminal blocks and +5 volt to another. Each set of terminals is bussed via a screw strip on the top of the terminals. The +12 and -12 volt lines go into a single terminal each. From the terminal strips the power is distributed to the rest of the panel.
The +5, +12, and -12 volt supplies are wired to the calibration lamps and the 24 Channel Analog Input board. The Analog Input board not only uses the power supplies for its logic, but the lines are also monitored by the computer via this board. Not shown in this drawing are the +5 volt and ground wiring that goes from the terminal strips and the connector panel on top of the Galil Amplifiers.
The +28 volt supply is wired with heavy gauge wire to the servo amplifiers. There is also a smaller set of wires taking the +28 volts to the Analog input card. These wires enable the computers to monitor the supply voltage.
Temperature monitoring EL-3304:
Temperature monitoring
Because the electronics are enclosed in sealed lockers, any failure in the cooling system could cause the temperature in the locker to quickly rise to levels that could damage the components. This circuit is designed to prevent such a failure from destroying the electronics it that locker.
The main power for the locker is applied to terminals 1-3 of JP1 (left side of the drawing). The ground and neutral lines are sent directly to the output connector (JP2-2 & 3). The hot line is routed through one of the contact of the heavy duty relay to JP2 pin 1.From this connector the power is sent to the rest of the locker.
The hot line is also applied to one side of the relay's coil. The other side of the coil can be connected to the neutral line by either of two means. A mechanical thermostat is mounted on the Opto-22 relay rack panel. The thermostat has a trip point of 80 degrees F. If the temperature exceeds the trip point the contacts of the thermostat will close, applying power to the coil of the relay. An Opto-22 solid state relay module (channel 6 of panel 1 for controller #0 and channel 6 of panel #4 for controller #1) can also energize the coil if commanded to do so by the control computer.
If the relay's coil is energized it will open the contact (the top contact of the relay) that supplied power to the rest of the locker. It will also apply power to the externally mounted sonalert to alert the user that the power has been disconnected. The bottom contact in the drawing will latch the relay on so that power will be prevented from being reapplied until the manual reset button is pressed.
Mounted on the EL-3304 box is a red button labeled 'RESET'. If this button is pushed, power will be remove from the relay coil. This will restore power to the locker. If this circuit is triggered there is a serious cooling problem. Power should not be restored until the problem is found and corrected. By design, this can not be done remotely. Thus the circuit demands that a person must open the locker, diagnose and fix the problem,and finally press the button to reset the protection circuit.
Galil locker fan control EL-3305:
Instrument Locker Fan Control
This drawing shows the wiring for the cooling fans in lockers #1 and #3. The fans in locker #2 are controlled by output bit Dout15 of the CCD Controller's Utility board (see EL-3316.) The Galil controllers turn the fans off and on to regulate the temperature inside their lockers. It monitors the temperature via a LM-35 temperature sensor mounted on the EL-3306 Analog Environment Monitoring board. In each locker, output channel 5, bit 30, is set to energize an Opto-22(TM) output module which connects the power to the fans. The temperature regulating is done in the code inside the Galil controller and does not require the supervisory computer's intervention. However, the supervisory computer does read the temperature from the Galil and let's the user know if there is a problem.
Sheet 1
Analog Input Wiring Sheet 1
Controller #0:
This drawing shows the wiring of the various analog signals that the Galil controller is able to monitor. The left side of the drawing shows the input signals coming in via connectors J2-J4. At the top, J4 shows only one temperature sensor input. This sensor lives inside a DB-9 connector that provides a second local temperature to the control computer. There is also a sensor mounted on the PC board. The board mounted sensor is used to close the control loop for the cooling fans in locker #1. The sensor in the DB-9 backshell provides another input for a 'sanity check'. The cooling loop for the locker is run locally in the Galil Controller's code and does not require intervention from the control computers in the data room. The cooling loop consists of the temperature sensor and a heat exchanger with two fans. The Galil controller has code that monitors the temperature and turns the heat exchanger fans on and off. The temperature data is also monitored by the instrument computers. The control computer has the ability to turn the AC power off to the locker if the temperature goes too high in the locker. This could happen if the fans for any reason fail.
The DB-25 connector, J2, connects six of eight possible temperature signals to the Galil controller. These are used to monitor various temperatures in the instrument. These are:
1. Instrument internal temperature. This sensor is mounted in free air near the science camera.
2. The temperature of the CCD dewar fill tube. The sensor is located on the fill tube.
3. The temperature of the science camera. The sensor is mounted to the camera body.
4. The temperature at the coolant outlet pipe measured at the coolant manifold.
5. The temperature at the coolant inlet pipe, again measured at the coolant manifold.
6. The temperature at the collimator at the alignment hole flange.
At the lower right-hand side of the drawing are shown the connections to the various power supplies that are monitored. Connector J7 supplies connections to the external power supply. The voltages monitored are the +5 volt, +12 volt, and -12 volt power. Above that are connectors J5 and J6. These are used to monitor the +28 volt servo motor power supply. In this case, only J5 is connected. J6 is available in case there are more that one supply used.
The top right-hand of the drawing shows the interface lines between the analog board and the Galil controller. The three digital output signals out5, out6, and out7 are used to select any of eight inputs. There a total of 24 inputs to the card. Each of three groups of eight is connected to an eight channel multiplexer. The three multiplexer outputs then are wired to three of the Galil's analog inputs via Analog inputs 1-3.
Sheet 2
Analog Input Wiring Sheet 2
This drawing shows the wiring of the various analog signals that the Galil controller is able to monitor. The left side of the drawing shows the input signals coming in via connectors J2-J4. At the top, J4 shows two temperature sensor inputs. The top sensor is mounted in the calibration lamp assembly - known as the 'photon torpedo' - and is used to close the cooling loop for the lamps. There are two ducts leading from the electronics locker to the calibration lamp housing. At one duct, a fan pushes cool air from the locker into the lamp assembly. The other duct returns the warmed air back into the locker where it is cooled again by the heat exchanger. Another sensor lives inside the DB-9 backshell and provides a second local temperature to the Galil controller. There is also a sensor mounted on the PC board. The board mounted sensor is used to close the control loop for the cooling fans in locker #3. The sensor in the DB-9 backshell provides another input for a 'sanity check'. The cooling loop for the locker is run locally in the Galil Controller's code and does not require intervention from the control computers in the data room. The cooling loop consists of the temperature sensor and a heat exchanger with two fans. The Galil controller has code that monitors the temperature and turns the heat exchanger fans on and off. The temperature data is also monitored by the instrument computers. The control computer has the ability to turn the AC power off to the locker if the temperature goes too high in the locker. This could happen if the fans for any reason fail.
The DB-25 connector, J2, connects six of eight possible temperature signals to the Galil controller. These are used to monitor various temperatures in the instrument. These are:
1. Air temperature at the Prism Stage as measured at the edge of the prism.
2. The air temperature in front of the slit with the sensor in free air just above the slit mask wheel.
3. The air temperature at the upper triangle (top of instrument).
4. The temperature at the coolant outlet pipe measured at the coolant manifold.
5. The temperature at the coolant inlet pipe, again measured at the coolant manifold.
6. The air temperature of the telescope dome measured in front of the hatch.
At the lower right-hand side of the drawing are shown the connections to the various power supplies that are monitored. Connector J7 supplies connections to the external power supply. The voltages monitored are the +5 volt, +12 volt, and -12 volt power. Above that are connectors J5 and J6. These are used to monitor the +28 volt servo motor power supply. In this case, only J5 is connected. J6 is available in case there are more that one supply used.
The top right-hand of the drawing shows the interface lines between the analog board and the Galil controller. The three digital output signals out5, out6, and out7 are used to select any of eight inputs. There a total of 24 inputs to the card. Each of three groups of eight is connected to an eight channel multiplexer. The three multiplexer outputs then are wired to three of the Galil's analog inputs via Analog inputs 1-3.
Sheet 3
Analog Input Wiring Sheet 3
This sheet shows the wiring of connectors J2 and J4 of both Galil controller Analog Input boards. A junction box has been installed on the outside between lockers 1 and 3. Cables come from each of the Galil panels and connect to the various temperature sensors. See sheets 1 and 2 above for the details of the sensor placement.
Sheet 4
Analog Input Wiring Sheet 4
This sheet shows the wiring of a special 'Y' cable used to allow connection of the Renishaw 'Status' signals from both of the Galil amplifier connector panels. At the left are the connections from the 24 Channel Analog input board EL-1230. These are divided into two groups allowing for four inputs from each of the amplifier connector panels. The Renishaw encoders provide an analog output proportional to the quality of the signal it is receiving from its read head as an infra-red LED reflects off of the linear encoder tape. As this was an add on near the end of the project, the wiring took this form to allow reading all six of the Renishaw encoders in use via one Analog Input board. The 'Y' cable brings in the signals from the triple wheel assembly on channels 1B, 2B, and 3B, and the signals from the three collimator actuators on channels 5B, 6B, and 7B. Later, signals were added to bring in a air pressure signal on channel 4B and a ion pump current signal on channel 8B. This connector is on the right-hand side as you face the board.
Air pressure switch wiring EL-3309:
Air Pressure Switch Monitoring
This drawing shows the wiring and connections for the air pressure sensor. The sensor is a Omega PSW-522 and is wired as normally open. When the air pressure goes below the set point, the circuit is closed and channel 16 on panel 3, bit 89, is asserted. The software monitors this bit and will not allow any motion that requires air pressure to be initiated(?)
The air stages in use are the hatch cover and the CCD shutter.
Coolant flow switch wiring, EL-3312:
Coolant Flow Monitoring
The coolant temperature and flow are monitored by the supervisory computer. The temperature transducer is a LM-35 precision centigrade temperature sensor that is attached to the coolant line at the manifold. A Proteus Model 0100B110F2 flow switch will close it's contacts if the flow falls lower then 0.2 gallons per minute. At that point, channel 20 of Opto-22 panel 3, bit 93, will be asserted. The Supervisory Computer monitors these conditions and if they occur the user will be informed.
TV camera power control, EL-3313:
Photometrics CCD TV Camera Power Control
The Supervisory Computer controls the power to the Photometrics PXL TV Camera by setting or resetting channel 4, bit 29, of Opto-22 panel 1. Because Galil controller #0 is in a different electronics locker, a separate extension cable is run between lockers 2 and 3. The control circuit switches an AC outlet located on the Galil panel that is labeled TV.
The drawing shows the four different cables that connect the controller to the camera head. These cables leave the electronics locker and to the camera mounted to the optical sub-structure. The camera controller uses an AIA interface board to send out the video information. The cable from the AIA board goes to an AIA-to-SCSI (Photometrics model A2S) converter box. This box is converts the AIA signals into SCSI format. The output of the A2S box is then cabled to a Black Box model IC49 5A-R2 SCSI-to-fiber converter. The data is then sent to the computer room via a duplex fiber optic cable.
Ion pump controller wiring, EL-3315:
Ion Pump Controller Wiring
The CCD dewar ion pump controller, Varian model 921-0015, is mounted in electronics locker #1. The high voltage cable and ground strap are routed from the back of the controller to the dewar through the cable access hole cut at the top of the locker.
Two modifications have been made to the controller (see EL-1027). First, the output current is monitored by reading the voltage across a 10 ohm resistor in series with the output. If the measured output goes higher then 3.5 milliamps, the added relay R1 will drop out and remove the AC input to the ion pump controller. This keeps the ion pump from over heating due to loss of vacuum or from the dewar warming up. A second set of contacts on relay R1 supply an AC current to the interface connector on pins 13 and 14. These are in turn wired to J44 on the Galil panel and on to input channel 23, I/O bit 96, on the Galil controller. (See EL-3306 in this section and schematic EL-1027B in the Miscellaneous Drawing section.) To restart the controller manually, the operator may depress and hold the red restart button on the face of the controller until the current goes below 3.5 milliamps on the meter.
The second set of modifications allows the ion pump controller to be operated remotely by the supervisory computer via the Galil controller. The push button is paralleled with a Opto-22 G4OAC5A relay that closes the internal relay R1. With this relay activated the ion pump controller will again apply voltage to the ion pump. By monitoring the current across the 10 ohm resistor the supervisory computer can tell when the current is low enough for the ion pump controller to stay on. The software knows that the restart push button can only be activated for short times or the ion pump can overheat.
The final modification to the ion pump controller allows us to read if the front panel rotary switch is in the correct position. An extra wafer has been added to the switch and wired so that if the switch is not left on the 5KV position the current reading may be inaccurate. This is because the current reading on some of the lower scales are not read correctly. By knowing that the switch is in the correct position, the software knows that it is reading a valid current input.
CCD Controller locker cooling fan control, EL-3316:
CCD Fan Control
Electronics locker #2 does not contain a Galil controller so a bit from the CCD Controller is used to turn the cooling fans on and off. Bit Out14 is wired to pin-4 of an 8 pin connector on the back panel of the controller. This signal and +5V are wired to a Crydom D1225 Solid-State relay. When the signal is pulled low by the software the Crydom completes the circuit that turns on the cooling fans. The temperature of the locker is sensed with a sensor mounted on the SDSU Utility Board.
