Technical data

Chapter 7: Service and Maintenance
Diagnostic Tests
(9/00) 7-21
Internal Testing
Access the Diagnostics program block and perform the tests to detect internal problems.
See Chapter 3.
• Memory— to test memory on the controller board, flash memory, RAM, and the
EEPROM.
• Display— to test each segment of the upper and lower display areas and the display
ROM and RAM.
• Keyboard— to test each key of the keypad, and/or an external PC keyboard.
• Scale— to test the weighing functions of a scale that is connected or simulate
weighing functions in the expanded x 10 display mode.
• Serial ports— to test the serial I/O ports, including a loop back test.
• Parallel ports— to test the discrete I/O ports.
• Network— to test the network connections.
20 mA /RS-232 Printer
Tests
20 mA Terminal Output Test
If you suspect the terminal may not be transmitting data to the printer when using 20 mA
current loop, follow this test procedure:
1. Remove power from the terminal and the printer and disconnect the data cable from
the printer.
2. Connect the red voltmeter lead to the + 20 mA receive pin on the printer end of the
cable.
3. Connect the black voltmeter lead to the - 20 mA receive pin on the printer end of the
cable. Set the meter to read DC milliamps.
4. Apply power. The meter should read as follows:
• For 300 to 9600 baud in Demand mode, the meter should display a stable
reading between 18.0 and 40.0 mA. Any reading below 18.0 mA or above
40.0 mA indicates a malfunction in the sending device.
• For 2400 to 9600 in Continuous mode, the meter should fluctuate
continuously between 16 mA and 22 mA. The constant fluctuation on the meter
display indicates the scale/indicator is transmitting information. To test the
Demand baud rates, press PRINT on the terminal. The display should fluctuate
from 1/2 to 3/4 of the initial reading, then become stable again. This indicates
the terminal has transmitted data.
RS-232 Terminal Output Test
Use the following procedure to determine if the RS-232 serial port is operational.
1. Remove power from the terminal and the printer and disconnect the data cable from
the printer.
2. Set the voltmeter to read 20 volts DC.
3. Connect the red lead to pin 2 of the printer end of the data cable and connect the
black lead to pin 7.
4. Apply power. The meter should read as follows:
When measuring the higher baud
rates in the Demand mode, the
meter display will fluctuate for a
shorter period of time.