Log entry time 20:59:42 on June 2,2001

Entry number 61614

keyword=EPICS control instructions for He3 target

NOTE: Things are still changing, so if something isn't exactly as described,
use your best judgement.

0.1 How to Start the GUIs

At this time, the GUIs are only accessible from the hacsbc2 computer.
Under the "Hall A Main Menu" GUI, you'll find the choice
"Polarized He3 Target Controls". If you click on the button next to
that choice, the GUI "Polarized He3 Target Main Menu" will appear.
At this time there are six choices: RTD Readback, Ref. Cell RTD Readback,
Half-Wave Plate Motion, Vertical Target Lifting, Main Laser Control and
Oven Control. If you click on the buttons next to these choices, the
subscreens pop up.

0.2 RTD Readback

This GUI displays the temperature at various places along the target cell.
The bottom five monitors display the helium cell temperatures, while the
top two monitors display the RTDs on the pumping cell.

The alarm limits for these channels can be set by clicking on the
"Set Alarm Limits" Gui. Currently these alarms reset when the IOC is rebooted,
but they will be built-in someday.

0.3 Reference Cell RTD Readback

This GUI displays the three RTDs on the Reference Cell. At this
moment, they read bizarre values, but soon they will read the correct
reading, which is around 40 C. When the target is filled with gas
(nitrogen, He3 or He4) you'll find the pressure next to the variable
"Gas Pressure". The vacuum level is found by "System Vacuum". There
are helium jets to cool the ends of the target and reference cell. The
helium flow in liters/minute is found by the variable "Helium Flow".

0.4 How to Move the Half-Wave Plates

The target polarization can be reversed by insertion or removal of a set
of half-wave plates. The GUI for the half-wave plate control is invoked
with the "Half-Wave Plate Motion" button. The lenses only have two
positions, IN the beam path and OUT of the beam path.
The speed, acceleration, deceleration and number of steps can be defined
for the motor, but the defaults should be
fine. The distance between the IN and OUT position is 1,200,000 steps.
That number should be in the "Steps to move" box. It's the default.

The "motor position" box tells the current position of the half-wave
plates. Zero is the defined IN position and 1,200,000 is the defined
OUT position. If the half-wave plates are OUT and you want to move them
IN, click on the "GO" button
under "Move half-wave plates IN". Next to this button an "Active" sign
will appear, and the word "Moving" will appear next to the "Motor
Position" box. When the move is done, the words will disappear and the
"Motor Position" box will read "0". If the half-wave plates are IN and
you want to move them OUT, click on the "Go" button under "Move half-wave
plates OUT". The same words will pop up until the movement is finished,
then the position in the "Motor Position" box will read 1200000
(1,200,000, the out position). The is a camera set up look at the
half-wave plate motor base, and you should be able to see the carriage
over the words "IN" and "OUT" to visually verify the position.

The RS-232 communication for this device is sometimes flaky.
If the message "RS-232 failure - press the button ->" appears next
to the purple button in the middle right of the GUI, press this
button until the fault clears.

If you need to halt the motion, there's an "Emergency Stop" button located
in the upper right. Click on "HALT" and hopefully the motion will stop.
Do this if you see the motor about to drive off the motion plate
onto the floor. There are software limits set, so this shouldn't happen,
but just in case . . .

0.5 How to Move the Target

The target lifting GUI is invoked with the "Vertical Target Lifting"
button on the "Polarized He3 Target Main Menu" Gui.
There are five allowed target positions: Reference Cell, Empty Target,
BeO+12C foils, Polarized He Cell and Pick-Up Coils. These positions are
selected by clicking on the appropriate choice and then pressing the
"Start" button. The motion doesn't begin until the "Start Motor" button is
pressed. There is currently no way to cancel a motion one it has begun,
so make sure you've clicked on the correct target before you click start.
When you click on a target a number will appear in the "Dist. Abs."
readback. That number is the preset target position, in encoder
revolutions from a home switch. That number can be compared with allowed
positions by clicking on the "Display Allowed Positions" button. The
desired position, velocity, and acceleration can be set manually.
This GUI is invoked using by clicking on the "Manual Controls" button.

While the target is moving, the current position is read back
automatically. You can also click on the "Get Position" button and
the current position will be display in the blue box next to the
button. The yellow box to the right of the "Position"
button display the word "Intermediate" when the position doesn't
correspond to a preset target position. It display the target name
when you are at a preset target position.

In the bottom left-hand corner, there's a "Motor Status" box. This box
tells the state of the motor and limits. Everything should read "OK".
If something is wrong, the words "Failure" or "Latched" will appear.
The readback in this box is only valid if the RS-232 communication is
working correctly. There's a button in the upper-right-hand corner labelled
"Test RS-232". If communication is ok, the message "RS-232 OK" will appear
above this box. If it's not ok, the message "RS-232 communication
fails !!!" will appear next to the button. Click the
"Test RS-232" button to clear the fault. If it doesn't clear after 5
clicks or so, call the Target on Call person. There is a small paragraph
of help available under the "Help" button if the RS-232 is giving you
trouble.

If the power on the motor ever goes off, or if the motor gets confused,
the home routine must be run. This is accessible under the "Run Home
Routine" button. The home switch corresponds to the empty target, which
is in the middle of the target ladder, so there are targets above and
below the home position. Target below the home switch have positive positions
assigned to them; the ones above the home switch have negative positions
assigned to them. The home routine needs to approach the home
switch from below, so it can only be run if the target was in a positive
position before the failure, e.g. in the BeO+12C position, Polarized He Cell
or Pick-Up Coils position. If this was the case, click on the "Run Home
Routine" button and then the "Go Home" button. If this wasn't the case or
if you don't understand what's going on, page the Target on Call person.
Try not to run the home routine unless the target was in a positive
position, because otherwise you'll run into one of the limit switches because
the home routine will move up, looking for the home switch which isn't
there.

0.6 Laser Control

The GUIs for the lasers are invoked by the "Main Laser Control"
button. Pressing this button will call the "Laser Controls" GUI.
This GUI currently has 8 buttons, one for each of the six lasers
actually used to pump the target (1-6), one spare (7) and one
spare of a different model (8). Lasers 1-7 are know as "Coherent"
Lasers, which is their brand. Laser 8 is an "Opto-Power" Laser,
the brand used during the GDH experiment. Lasers 1-3 are
aligned for pumping in transverse mode, while lasers 4-7 are
for pumping in Longitudinal mode. Laser 8 is a true spare and is
not aligned as of now.

To control the lasers, click the button next to the desired laser.
This will bring up a GUI entitled "Coherent Laser X control screen
(port Y)", depending upon the laser chosen. You'll see the
status of this laser next to the "Get Status" button.

If the laser is off and you want to turn it on, first
set the desired temperature and current in the "Set Temp" and "Set
Current" enter boxes. Make sure to hit return to send the values to the
database. The defaults should be around ~40 A and ~15 C.

To start the lasers, first press the "Enable" button. The state of the
laser will change to enabled. Then press the "Start" button. The
laser will turn on. There is a camera pointing at the lasers. On
the camera monitor you should see a light come on on the appropriate
laser. The lasers are labelled vertically, with 1 at the bottom and 7 at
the top.

To turn a laser off, press the "Stop" button. You should see the
light go off on the camera monitor and the status on the GUI will change
to "0" (disabled).

0.7 Oven Control

The oven control GUI is invoked by pressing on the button next
to "Oven Control" on the Main GUI. This will bring up a GUI
with a readback of "Oven Heater Power" in the middle of it. Currently
this GUI will come up unresolved (i.e. all boxes white) because the
control is still under testing. Use the manual control procedures for
control of the Oven, even if the GUI starts working some day.

The EPICS control has been tested as much as possible, but there may
still be some bugs in it. The first thing to do if something
doesn't respond is to reboot the IOC. The IOC for the helium target
control is called "iocha26" and it sits down in the Hall, so it
may get messed up because of radiation. To reboot it, choose
the "Tools" option from the "Hall A Main Menu" GUI. In the upper-right
of this GUI, under "Miscellaneous" you'll find a "Crate Resets" button.
This will invoke the "Hall A Slow Controls Resets from Relay Cards" GUI.
Click on the "click to reset" button next to the "Polarized
Helium target VME Reset" choice. The polarized He3 target control screens
will go white for a while, and in about five minutes they should reset.
Hopefully the problem you were having is then fixed. If this doesn't
work, or if this button hasn't been implemented yet, page the Target-on-Call.

User name K. McCormick

Log entry time 20:59:42 on June 2,2001

Entry number 61614