IM-P192-02
MI Issue 2
51
Symptom
Possible cause
Action
TVA produces
large amount of
noise (banging and
clattering)
Upstream/downstream
installation lengths
incorrect.
Re-install following the installation
guidelines (Section 3).
Non zero flow
indicated when no
actual flow is in the
pipe.
Unit not zeroed at
commissioning.
4 mA output not
calibrated.
4 mA retransmission set
to a value higher than
zero.
Interference.
Zero unit.
Calibrate 4 mA output (Section 4.6.5).
Reset 4 mA.
Check earthing.
RS232/Modbus
communications
not working
CTR/DTS not
connected/powered.
Connect CTR/DTS terminals
Additional fault finding for versions with RS485 conversion board fitted.
Symptom
Possible cause
Action
No power and no
diodes lit up.
No power to terminals
4 and 5
Check power supply.
Power to terminals 4
and 5 wrong way round.
Connect to terminals 4 and 5 correct
way round.
No communication,
Green diode lit
only.
No query received from
computer system.
Check communication cable
connection.
Wrong configuration of computer
system (wrong port, etc.)
No communication,
Green diode lit,
Yellow diode
flashing, blue
diode off.
A and B wires
connected wrong way
round.
Connect A and B wires correct way
round.
Baud rate set wrong.
Change baud rate.
ASCII / Modbus
selected wrong.
Change ASCII to Modbus or Modbus to
ASCII.