Fluke 900 - Manual (Page 40)

Seiftest FLUKE 900 SERVICE MANUAL
TEST 50
UART_TEST
The RSCNT3, RSCNT2, and RSCNTl lines on the Micro Board control the configuration of
the rs232 port (DTE.DCE). These lines are put into a normally illegal state that allows the
outputs of the UART to be fed into the inputs. This can be done in two ways and all tests are
done in both configurations.
There are two tests: the first tests the control lines (DTR, CTS,...) and the second transmits
data between the transmitter and receiver. The second test is not done if the first fails.
1. Test the control lines (byte 2 & 3 results). Each of the control lines is tested with the
other control line in a fixed state, first hi^ then tested again with it low. At the top of
the results for each byte the setting of the configuration lines is shown. For each test
the state of the state of the two ou^ut control lines is shown as well as the input line
and what state is expected on it
2. Test the data lines. This test is NOT done unless test 1 passes. The baud rate is
programmed to 9600 regardless of the setting of the rs232 port. At the end of the test
it is reprogrammed with the correct value. A small block of data is sent and compared
with what was received. The receiving of data is interrupt driven so that this test may
fail if there is something wrong with this part of the board. The setting of the
configuration lines is shown for each test.
RESULT BYTES
BYTE 0 = all bits 0
BYTE 1
b7-0
b6-0
b5 - 0
b4-0
b3-0
b2 - 0
bl -1 if serial data test failed with RSCNT[3,2,1]=001
bO -1 if serial data test failed with RSCNT[3,2,1]=110
NOTE RSCNT[3,2,1] means that control signals RSCNT3, RSCNT2, RSCNTl to Ul,
U2, U7 on the Micro Board (page 9 of schematics) were held in the states shown
during the test.
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