Configuration
164 UDC3500 Universal Digital Controller Product Manual 3/07
Function Prompt
Lower Display
Selections or
Range of Setting
Upper Display
Parameter
Definition
LOOPBACK
LOCAL LOOPBACK—Tests the RS-485
communications port. This feature is not used for
any other communications port.
DISABLE
DISABLE—Disables the Loopback test.
ENABLE
ENABLE—Allows RS-485 Loopback test. The
instrument goes into Loopback mode in which it
sends and receives its own message. The
instrument displays PASS or FAIL status in the
upper display and LOOPBACK in the lower display
while the test is running. The instrument will go into
manual mode when LOOPBACK is enabled with the
output at the Failsafe value. The test will run until the
operator disables it here or until power to the
instrument is turned off and on.
ATTENTION The instrument does not have to be
connected to the external RS-485 communications
link in order to perform this test. If it is connected,
then only one instrument should run the Loopback
test at a time, as the instrument running the
Loopback test transmits on the RS-485 bus. The
host computer should not be transmitting on the link
while the Loopback test is active.
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