Crystal Grower Controller Usage

Crystal Grower

Controller Usage Manual

Warning: This Manual page is under construction and is currently not very complete.

Features and Capabilities

The controller currently has the following features and capabilities:

Translation at a set rate (mm/hr) and manual motion
Rotation at constant rates (not during translation)
Translation halted due to: TC breakage or limits reached (errors)
Generator shut down when translation halts due to error.
Translation position monitored via digital indicator and display of percent error.
Logging of Upper and Lower TC temperatures, Power, both position readings. This data is available in real time over the web.

Keypad Layout

The keypad of the controller is shown below. The functions of the keys follow.

Keys 0-9, ±, .: Numeric entry keys for entering parameter values
Back Space: Backspace in entry mode or up a menu level in menu mode
Next: Next menu on current level
Previous/Escape: Previous menu on current level or Escape from entry mode
Enter: Enter lower menu level or entry mode. In entry mode accept entered value.
Run: Start run mode, translation at programmed rate and status reporting
Rotate: Rotate at selected rate, alternates direction of rotation each use
Stop: Stop any of: Run, Rotate, manual up or manual down motions.
Start high speed manual translation up.
Start high speed manual translation down.
Zero Pos: Zero the translation position counter displayed on LCD.

LCD Display

The LCD display has four rows, the contents of each are described below.

Row 1

Mode Status (Stopped in image above) and Upper TC temperature (22.) are displayed on this line.

Row 2

Translation position (0.000) and Lower TC temperature (20.) are displayed on this line.

Row 3

In Run mode the translation error is displayed on this line, in other modes status messages are displayed here. (This line is blank in the image above.)

Row 4

This line is used by the menu system. In the image above it has the top level Translation Menu displayed.

Menus

The last line of the LCD display is used for the menu system. The menu structure is shown below, only the menus in bold currently work:

Translation:
- T Rate Set the translation rate for the Run Mode (mm/hr)
- Translation Mode Sets when translation starts after the Run key is pressed.
  - Continuous (Y/N) Currently always Yes.
  - At Time (Y/N)
  - Set Time
    - at Sec
    - at Min
    - at Hr
    - at Day
    - at Month
    - at Yr
  - At Temperature (Y/N)
  - Set Temperature
    - at Temperature
    - Delay (mins)
Rotation:
- Rotation Rate Set the rotation rate for the Rotate Mode (rpm)
Temperature:
Control:
- Reset Error Reset error condition that stopped the Run Mode
- Boot Mode(1/8) Set the boot (power on) mode 1=Dynamic C, 8=User Program (For programming use only)

The menu system uses the bottom line on the LCD display. Only one menu is currently visible at a time. If a menu contains sub-menus then pressing the Enter key when this menu is displayed causes a sub-menu to be displayed. The Next and Previous keys move through the menus on the current level. Pressing the Enter key on a menu that takes a value causes =? to be displayed at the end of the menu. At this point a new value can be entered using the numeric keys. Pressing Enter accepts the new value, pressing Escape discards any entry. The Back Space key erases entered characters in the entry mode or moves you up to a higher level in the menu structure.

Setting the Translation Rate

Note that the controller can only produce a discrete set of translation rates. Thus when you enter a rate the value shown on the T Rate menu will not be exactly the same value as you entered in many cases. The value shown is an attainable rate that is closest to the rate you entered.

Error Conditions

During the Run Mode, several error conditions can stop the translation and shut down the generator. These are:

Broken Upper Thermocouple
Lower Limit hit

When this occurs, the error will be displayed instead of the current mode on the first line of the LCD display. Additionally it is not possible to start the run mode again until this error is reset. To reset the error, press the Enter key on the Reset Error menu item of the Control menu.

Status Logging

In the Run Mode, the controller sends a status message to crystal.aem.umn.edu over its serial connection every 60 seconds. This message contains:

Upper TC Temperature (degrees C)
Lower TC Temperature (degrees C)
Actual Translation Position from digital indicator (mm)
Translation Position based on stepper motor pulses (mm)
Power commanded by Eurotherm (percent)
Status = 10 * run_mode + error_status

This logged data is available from http://crystal.aem.umn.edu/status. Each time the run mode is entered a new data file is started. These data files may be viewed or their contents plotted over the web. The top few lines of one of these data files is shown below.

C upper,lower,actpos,tpos,power,status,time
22,18.92,0,0.001505,0.77097,10,17:38:55,06/05/98
22,18.58,0.16,0.170315,0.642475,10,17:39:55,06/05/98
22,18.62,0.33,0.338875,0.77097,10,17:40:55,06/05/98
22,18.78,0.5,0.507435,0.77097,10,17:41:55,06/05/98
22,18.85,0.67,0.676497,0.77097,10,17:42:55,06/05/98

The first line is a comment that labels the columns which are comma delimited.

The status values are calculated from 10*run_mode + error_status, where the possible values of run_mode and error_status are given next:

Run_mode is: 1 = Running; 0 = Stopped

Error_status is: 0 = no error; 1 = Upper limit hit; 2 = Lower limit hit; 3 = Broken Upper Thermocouple; 4 = Interlock detected

Thus when the grower is running normally the status value will be 10 and when the grower has been stopped manually the status value will be 0. Any value less then 10 and greater than 0 means the translation stopped due to an error.