DELCOM
	717/727 CONDUCTANCE MONITOR
	DATA SCHEME

	Serial port settings are:  4800 Baud, 8 Data Bits, No Parity, 1 Stop Bit

	The data communication scheme used is a polling system in which the 
	PC sends a request to the 717/727 by sending as data the channel 
	number of the 717/727 instrument.  On single channel systems, this 
	number is set to 16 binary (0001 0000, or hex 10).  After the 717/727
	reads its channel number on the serial port, it sends a six byte string.
		
	The format is as follows:

	Byte 1:  This byte set to 11111111 (hex FF), and is used only as the 
	marker for the beginning of the byte string.  The software in the PC 
	tests for this byte before it accepts the following five bytes as 
	valid.
	Byte 2:  This byte is used to send information on sign, range, and 
	overange conditions.  Only the three lower bits are used, the other 
	bits are always 0, except bit 7 which is always 1.

				      01000000
					   |||----Sign,  1 = Negative
					   ||-----Range, 1 = High Range
					   |------Overrange = 1

	Byte 3 and 4:  These bytes give the conductance value, with byte 3 
	being the most significant.
	Byte 5 and 6:  Normally not used.

	Note:  The cable type required is an IBM AT type Serial Cable.
	       (25 Pin Straight Thru, or 9 Pin Female to 25 Pin Male)