Amplicon 485HF9, Инструкция по эксплуатации

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Model 485HF9
Page 21
4. TESTING AND TROUBLESHOOTING
4.1
Basic Testing and Fault Isolation
If the installation instructions have been correctly followed, and the serial communications port
is being used in conjunction with a proven software driver, then it is unlikely that any problems
will be experienced in establishing communications through the serial interface.
When difficulties do occur, the following notes may be helpful in isolating the problem area.
4.1.1 Testing with the Application Software
Before testing, ensure that the Model 485HF9 Adaptor is properly configured for the
application. Use the test mode of the application program, and If a problem occurs, it is often
possible to test the system using the looped back RS-232 port without the Model 485HF9
Adaptor. This test will identify that a problem is in the adaptor, its configuration or use.
4.1.2 Loop-back Testing Using a Simple BASIC Program
The Model 485HF9 Adaptor can be tested in isolation of external influences such as the signal
cables, other devices and the applications program by performing the following loop-back test.
It is necessary to link the terminals as shown in figure 11, and run the 4 line BASIC program
given below. A copy of a BASIC interpreter such as QuickBASIC or GWBASIC will be required.
FIGURE 4.1 TERMINAL LINKS FOR LOOP-BACK TEST
The base address of the channel under test should be set to 3F8 (COM1) and the channel
interrupt to IRQ4. The test can also be undertaken at 2F8 (COM2) and IRQ3 by changing the
first line of the program accordingly.
To test the
RS-422/485 port, the following 485HF9 Adaptor configuration settings must also be
checked. This is the default configuration.
J1 External Tx Enable
J2 Terminator Resistor In
J3 Echo-back ON
The test sends the message "Loop-back test passed" from the RS-422/485 port and reads it
back into the LB$ variable. The message is then printed once to the screen. This test
encompasses proper operation of both the RS-232 data and control interface and the RS-
422/485 data lines.
Model
485HF9
Adaptor
EN
1
GND 2
TX 3
TX 4
RX 5
RX 6
GND 7
VDC 8