GUIDE TO PURCHASE,
INSPECT AND MAINTAIN DIGITAL MEASURING INSTRUMENTS

1) Before using, clean the surface of the protective sticker of digital measuring instruments for several times with dry, clean cloth to remove water which might congeal.

Because water is weak electrolyte, the ionization of pH indicator and hydroxyl ion can be made. The ions will weaken or destroy capacitive signals to such extent that display will be in a state of disorder. So much attention should be paid to it in wet condition. At present, waterproof digital calipers have been put on the market, but it’s high in price.

2)Working Environment: Temperature:5-40 degrees; Relative humility: below 80%. Under such environment, it can prevent liquid containing eletrolyte from wetting the protective sticker. .

3) Never apply any electric voltage on a digital caliper or scribing on it by a electroprobe for fear that its circuit is destroyed.

4) Zero Adjusting:

Clean measuring faces( by rubbing a clean piece of paper between measuring faces for several times) and connect one measuring face with another. Exert pressure of about 3-5N between measuring faces. The measurement can be done upon setting zero by pressing Zero-setting Button. The pushing force exerted in zero-adjusting should be equivalent as far as possible to the one exerted in time of measurement in order to reduce measuring error.

5) Measuring Instruction:

Usually, Absoluste measurement is taken. “Zero” is set as mentioned above.

Difference measuring is usually taken to improve the accuracy in measurement. First, to place a block gage (about a size of a measured item) or to place other workpiece of standard size) between measuring faces with proper pressure (3-5N) and then set relative zero position with Zero button. The difference of standard size is displayed in time of the measuring of an item (Because the difference of value is small, it’s usually called difference measuring). The sum of difference and the above-mentioned standard size is the actual size of the measured item or the absolute size.

6) Data Outputting and Processing

At present, most digital calipers in China have a data port for data-outputting. It can be seen by taking off a small cap on the case of a slider. Meanwhile, it can be connected with a PC or a printer for data-processing or for the printing of analytic chart of measured figures via special cable. So the data port is usually termed an adaptor.

Interface working way: Synchronous serial.

Data: Binary code, 24 bits. Each datum will be transferred twice. The cycle is 300ms (20ms in fast reading state). Transmitting time: 0.5ms.

Four wires (from left to right): Negative power(-), Clock pulse CP, Data D, Positive Power(+).
Pulse range of data: 0 Level≤0.2V, Level ≥1.3V.
Clock Pulse CP: 90KHz, effective for high electrical level. 7) Replacement of battery

Abnormal display (digits flashing or even no display) shows a flat battery. A 1.55V silver oxide button cell (SR44) should be replaced.

The reason that a battery bought from a market doesn’t work satisfactorily lies in the automatic discharges of the battery and the wearing-down of its power. To get it solved, you may contact without hesitation the supplier for mailing of new batteries. Guanglu promises to provide domestic clients with batteries free of charge within three years.