trical current is automatically produced in proportion to the chlorine content of the sample. The membrane is
part of the membrane cap which screws on and off, for easy replacement in cases where it becomes torn or
punctured.
The microprocessor based electronics provide the capability for processing input signals, displaying data, and
providing multiple outputs. Mathematical computations on multiple variables are performed for accurate
determination of measured parameters which are related to other variables even in non-linear relationships
such as sensor temperature compensation.
The results are displayed on the 3 1/2 digit LCD Display on the front panel or are available on the input/output
connector board either as isolated current or voltage outputs. (Fig. 1)
An internal switch (S4-1) puts the microprocessor into a built-in simulator mode (mode 0) when used in
conjunction with front panel switches (S1, S3) and display, and R35 pot input parameters are simulated to
verify proper internal functioning of the A/D converter processing and outputs. This procedure is convenient
for setting up alarms, recorders, printers or computer outputs.
When the Model 924 analyzer is in operation, the microprocessor continuously monitors all the operational and
equipment functions. In this self diagnostic mode whenever a malfunction occurs an error message will be
present on the LCD display, messages being of 'two types: operational or equipment. Operational
malfunctions include questionable calculation results, insufficient data, excessive input noise, input
measurement or calculated results out of range. Examples of equipment problems that will generate a
malfunction display which include ROM fail check sum, RAM problems, identification error, card in wrong
position, switch failure, wrong or no input card. (For further details see Troubleshooting section. )
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