Filter
Top Products
Model T101 Instruction Manual Principles Of Operation
271
In its standard configuration, the analyzer comes with all three of these channels set up
to output a DC voltage. However, 4-20mA current loop drivers can be purchased for the
first two of these outputs, A1 and A2.
Output Loop-back
: All three of the functioning analog outputs are connected back to the
A/D converter through a Loop-back circuit. This permits the voltage outputs to be
calibrated by the CPU without need for any additional tools or fixtures
10.4.12. EXTERNAL DIGITAL I/O
This External Digital I/O performs two functions.
STATUS OUTPUTS: Logic-Level voltages are output through an optically isolated 8-
pin connector located on the rear panel of the analyzer. These outputs convey good/bad
and on/off information about certain analyzer conditions. They can be used to interface
with certain types of programmable devices (see Section 5.1.1.1).
CONTRO
L INPUTS: By applying +5VDC power supplied from an external source such
as a PLC or Data logger (see Section 5.1.1.2), Zero and Span calibrations can be
initiated by c
ontact closures on the rear panel.
10.4.13. I
2
C DATA BUS
I
2
C is a two-wire, clocked, bi-directional, digital serial I/O bus that is used widely in
commercial and consumer electronic systems. A transceiver on the Motherboard
converts data and control signals from the PC-104 bus to I
2
C. The data is then fed to the
relay board and optional analog input circuitry.
10.4.14. POWER UP CIRCUIT
This circuit monitors the +5V power supply during start-up and sets the analog outputs,
external digital I/O ports, and I
2
C circuitry to specific values until the CPU boots and the
instrument software can establish control.
10.5. POWER SUPPLY/ CIRCUIT BREAKER
The analyzer operates on 100 VAC, 115 VAC or 230 VAC power at either 50Hz or
60Hz. Individual units are set up at the factory to accept any combination of these five
attributes. As illustrated in Figure 10-18 below, power enters the analyzer through a
standard IEC 320 power receptacle located on the rear panel of the instrument. From
there it is routed through the ON/OFF switch located in the lower right corner of the
front panel.
AC line power is converted stepped down and converted to DC power by two DC power
supplies. One supplies +12 VDC, for various valves and valve options, while a second
supply provides +5 VDC and ±15 VDC for logic and analog circuitry as well as the TEC
cooler. All AC and DC Voltages are distributed through the Relay Board.
07266B DCN6485