Teledyne 1220 - Multipoint flammable gas and vapor detection system - Manual (Page 16)

2-6
2 Operational Theory Model 1220
Teledyne Analytical Instruments
Figure 2-3: Block Diagram of the Signal Processing Electronics
S2
Keyboard
A to D
Converter
Digital to
Analog
Converter
(DAC)
0-10 V dc
Concentration
4-20 mA dc
Concentration
RS-485
Power Supply 1
AC/DC
Power Supply 2
AC/DC
M
U
X
To CPU
Central
Processing
Unit
(CPU)
S1
± 12 V Test
+ 5, ± 15 V Test Analog Output Test
Relays
High
Failure
Caution
Display & LED
Indicators