Teledyne 6200E - Sulfides Analyzer - Manual (Page 230)

Theory Of Operation Model 6200E Instruction Manual
230 M6200E Rev: A1
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 6.12.1.1).
CONTROL INPUTS: By applying +5VDC power supplied from an external source such as a PLC or
Datalogger (see Section 6.12.1.2), Zero and Span calibrations can be initiated by contact closures
on the rear panel.
10.4.13. I 2 C Data Bus
The I 2 C data bus is used to communicate data and commands between the CPU, the
keyboard/display interface and the various switches and relays on the relay board. 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 keyboard/display interface (see Section 10.6.1.4)
and finally onto the relay board.
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.