K-Patents DD-23 - Manual (Page 25)

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6 Regular maintenance and troubleshooting
As the Divert control system is a pure digital system, no special maintenance is needed.
The
LIGHT TEST button on the operator panel (Figure 2.1) sends a signal to the micro-
processor, and the microprocessor switches all 12 LED lights on as long as the button
is pressed. This way not only the lights but also the processing system is checked.
To assist the identi󰅮ication of a faulty component, the information 󰅮low is given in Sec-
tion 6.1. Also the logic diagrams of Chapter 7 may be of help.
6.1 Information flow
The divert control unit is connected to the refractometers through an Ethernet con-
nection. The Control system asks for the measurement data from the instruments
several times each second. Based on the data received the divert operation decisions
are made.
Each refractometer performs its measurement functions independently. The instru-
ments also have their own internal diagnostics, which are used in the divert decision
logic, as well (see Section 6.2).
As the Divert Control System requests information several times a second, all commu-
nication problems are found immediately. In case one of the refractometers does not
respond to the control unit, the non-responding instrument is dropped from opera-
tion and the malfunction alarm is set.
An important information when troubleshooting communication problems is the let-
ter on the upper left corner of each refractometer (see Figure 5.2). If the instrument
has not received any data requests from the Divert Control Unit during the last second,
the letter turns into a question mark (
? ). If the letter is a/A/b/B , then the communica-
tion link between the Divert control unit and the instrument is fully functional.
6.2 Malfunctions
If the Divert Control Unit cannot communicate with a refractometer, or if the inter-
nal diagnostics of a refractometer indicate a measurement problem, the Malfunction
indicator (see Figure 2.1) is illuminated and the corresponding relay 8 or 9 (see Fig-
ure 3.3) is activated.
The diagnostic message of the refractometer can be seen on the transmitter screen
(see Figure 5.1). Some of these messages, e.g.
PRISM WASH , are only informative and
do not indicate a measurement problem. Table 6.1 below summarizes all diagnostic
messages and their effect on the Divert control system operation.