Fluke Biomedical 960CD-220 - Manual (Page 17)

Theory of Operation
Display/Channel ID
2
2-3
rate) and to count down the 2.4576 MHZ frequency from the crystal circuit to provide the 100 Hz and 4 Hz
timing signals used elsewhere in the controller. Table 2-2 lists the baud rates selectable via SW1.
SW3 provide the channel ID selects as shown in Table 2-3. This ID signal is buffered by Z7 and gated
onto the data bus at the appropriate time. Z7 also provides an interface to a remote keylock switch that is
used to select REMOTE, LOCAL, CALIBRATE, and TEST modes of operation.
LSI device Z8 functions as a driver/decoder. It drives a six digit, seven-segment display and decodes the
data to be displayed. Two IC's Z8 and Z9 are the current drivers utilized to drive the display. The display
module is normally located on the front panel of the Local Control Unit of the 960 Radiation Monitoring
System.
2.5 Switch Settings
Table 2-2 lists the baud rate settings for SW1. Table 2-3 contains channel identification selection
information for SW3. Reset switch SW2 is a momentary switch used to reset the controller.
Table 2-2. SW1 Baud Rate Settings
Switch Position
1 2 3 4
Output
L L L L Invalid
L L L H Invalid
L L H L 50 Baud
L L H H 75 Baud
L H L L 134.5 Baud
L H L H 200 Baud
L H H L 600 Baud
L H H H 2400 Baud
H L L L 9600 Baud
H L L H
4800 Baud; Standard
Setting
H L H L 1800 Baud
H L H H 1200 Baud
H H L L 2400 Baud
H H L H 300 Baud
H H H L 150 Baud
H H H H 110 Baud
H = Open
L = Closed
Table 2-3. SW3 Channel Identification
Switch Position Function
1 Non-Functional
2 Non-Functional
3 to 6
Encode the channel ID; position 3 is the least significant bit, position 8 is the most
significant bit.