MODEL 2G600
                       Automatic Sample Degaussing System

                     User's Manual and Technical Reference

                                  October 2002


CAUTION: When ramping to high field values, particularly those near the maximum 
coil capacity, it is important the allow the coil to remain on for only a short 
time period (<10 seconds) because of coil heating. The system has enough power 
capacity to raise the coil temperature high enough to damage the coil (T >160°C) 
if left on continuously. In computer mode, if the ramp cycle command is used, 
the system will automatically ramp down if tracking is not achieved.

2.3 Computer Interface

2.3.1 General features
The degaussing system is equipped with a computer interface that enables 
automatic degaussing under the control of an external computer. The interface is 
a serial RS232 data link. Connection to the degaussing system is made through a 
25-pin D female connector. Signals to the degausser from an external computer 
are on pin 2; replies from the degausser are on pin 3. Pin 7 is ground. No 
handshaking protocol is used. The communication baud rate is 1200 and the data 
word consists of 8 bits with no parity and one stop bit.

Because the data link is implemented in the degausser by a single board computer 
running a small basic program, the response time of the degausser to commands is 
slow. For instance, after sending a command DCA1000 (degausser configure 
amplitude 1000), the degausser will need about one second to process this 
information before it can accept another command. Suitable wait loops will have 
to be used in the external computer code to prevent unreliable communications.

2.3.2 Command response protocol
Commands to the degausser and responses all take the form of strings of letters 
or numbers (ASCII strings). Commands to the degausser must all be preceded by 
the ASCII letter D. Commands are of three types:

	1. Configure
	2. Execute ramp
	3. Send status

Configure commands set up the system parameters. These commands are denoted by 
the letter C, e.g., DCCS (Degausser Configure Coil X). Execute ramp commands are 
denoted by the letter E and cause a ramping of the field up or down or in an up 
and down (cycle) fashion. The send status command (DSS) causes the degausser to 
send back its status. A detailed listing of all degausser commands is included 
at the end of this section.

When the degausser is commanded to send its status, it returns a character 
string in the following format:

	S! R# D# C& A###.#

where
! specifies system status and can be Z = zero, T = tracking or ? = unknown
# specifies ramp rate parameter and can be any of the following numbers: 3, 5, 7, 9
# specifies delay parameter and can be any number between 1 and 9
& specifies active coil and can be X or Y or Z
###.# specifies amplitude and can be any number between 000.0 and 199.9

All commands to the degausser must terminate with a carriage return (ASCII 
character 13). A line feed should not be sent along with the carriage return. 
All responses from the degausser are also terminated with a carriage return.

When execute ramp commands are issued, the degausser will automatically answer 
when the commanded status is received. When a DERU (Degausser Execute Ramp Up) 
command is given, the system sends back a T when the field is tracking. If 
tracking does not occur, TRACK ERROR is sent back.

When a DERD (Degausser Execute Ramp Down) command is sent, the system sends back 
a Z when the field is at zero. If ramp down is unsuccessful, the degausser sends 
back a ZERO ERROR.

When a DERC (Degausser Execute Ramp Cycle) command is given, the degausser sends 
back DONE when the cycle is complete. If cycle is unsuccessful, the system sends 
back TRACK ERROR.


2.3.3 Synopsis of degausser protocol 1200 Baud, 8 bits, no parity, one stop bit

DCC
	Degausser Configure Coil (X, Y, Z) default axis Z
	(see note 1 below)

DCA
	Degausser Configure Amplitude (0000->3000) default amp 0000
	(see note 2 below)

DCD
	Degausser Configure Delay (1-9 seconds) default delay 1 second

DCR
	Degausser Configure Ramp (3, 5, 7, 9) default 3

DERU
	Degausser Execute Ramp Up

DERD
	Degausser Execute Ramp Down

DERC
	Degausser Execute Ramp Cycle

To get status, type:

DSS
	Degausser Send Status

Reply from controller:

S! R# D# C& A###.#

Status (!)		Z=Zero, T=Tracking, ?=Unknown
Ramp (#)		3, 5, 7, 9
Delay (#)		1 to 9 seconds: Used only in Ramp Cycle Mode
Coil (&)		X=X Axis, Y=Y Axis, Z=Z Axis, ?=Unknown
Amplitude (###.#)	00 to 3000


Note 1:
	When the tracking light in on, the command to configure coil axis will 
	be ignored. There are two circumstances that cause the tracking light to 
	turn on:
	
		1. Coil is energized and tracking
		2. Coil amplitude is set at zero (computer or manual) mode

	The second condition is the default condition on power up. To change 
	axis after power up, you must first configure the amplitude to be 
	nonzero.

Note 2:
	Amplitude commands must contain 4 digits, e.g., if an amplifier of 10 
	Gauss is required, use the command DCA 0010.