Badger Meter Vortex Meters - Manual (Page 45)

appenDiX b - TRouble shooTinG GuiDe
problem Resolution
Low loop voltage
The meter requires 15 volts DC at the power terminals. Measure this voltage at the
meter and ensure it is 15 volts or greater.
Incompatible operating
system
The Racine HART Interface will run on Windows 98, NT, XT, and XP. However, the
program works best with Windows 98 and XP. The Racine HART Interface has on
occasion run on PC’s with Windows 2000, but this operating system is not recom-
mended.
No HART resistor
A 250 Ω resistor is required between the power supply and the meter. However, this
resistor must not be between the meter and HART modem. The HART modem must
be connected to the terminals of the meter. See the wiring diagrams in Appendix A
for proper wiring and connection of the HART modem.
HART modem is not
connected properly
The HART modem must be connected to the 4-20 mA terminals of the meter. It is a
common mistake to connect the HART modem to the terminals of the power supply.
Make sure that the HART resistor is between the HART modem connection to the
loop and the power supply
It is also common for the HART modem to not make good contact to the loop wiring.
Often times the insulation is not completely removed from the wire.
COM1 is not available
The Racine HART Interface initially attempts HART communication using the COM1
serial port. However, COM1 may already be in use by a dial-up modem, some other
device or application. Make sure that other devices or applications do not use COM
1
If COM 1 is not available, select COM2 or COM3 using the “Com Port” dialog box
that appears after an unsuccessful attempt to connect to the meter (Clicking the
Connect button). After selecting the new Com Port, you must exit and restart the
Racine HART Interface for your change to take effect.
Insufficient PC
throughput
Older PC’s have slower processors with less processing power. You may want to
use a more powerful PC if you get occasional communication errors. If communi-
cation errors increase while other applications are also running on the PC, then
processing power is likely the problem.
PLC contains its own
HART resistor
It is common for a PLC input to contain its own HART resistor or current sensing re-
sistor. These resistors can range from 250 to 500 Ω. HART communication may not
work if the combined HART and PLC resistance is greater than 300 Ω. It is also pos-
sible for the HART resistor, PLC resistor, and loop resistance to reduce the voltage
at the meter to below the operating limits. If PLC input has 250 Ω resistor or larger,
do not use a separate 250 Ω HART resistor.
Multiple current paths
HART communication is achieved by current modulation on the 4-20 mA loop.
The current path to the meter must be limited to the two conductors of the loop. A
multiple current path problem is typically created when additional wiring is added to
power an external pressure sensor.
An isolated power supply must be used to power an external pressure sensor. Oth-
erwise, the HART resistor can only be placed in the positive side of the loop
It is important to note that the return side of the 4-20 mA flow loop is electrically con-
nected to the return side of the external pressure loop.
When cycling meter power, the Racine HART Interface must be closed and restart-
ed
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