The switched VLOOP power source is the output of the DC-DC 12/24V converter if it is turned on.
See the section 4.2.3-12V to 24V DC/DC Converter Control for converter information. The VLOOP
power source is the applied input power if the DC-DC converter is turned off.
• Turn on Digital Output 10 to turn ON the VLOOP output.
• Turn off Digital Output 10 to turn OFF the VLOOP output.
Internal Digital Input 10 indicates the status of VLOOP power. Digital Input 10 is set when VLOOP
power is on and is cleared when VLOOP power is off.
Note: When VLOOP is first turned on, the user application program must wait some period of time
for input readings to stabilize. This time period is dependent on the field sensors and
transmitters connected. Documentation for these devices should be consulted.
The VLOOP output is turned on when the LED power is enabled. This feature is provided for service
and diagnostics. Refer to section 11.3-LED Power Control for further information on this feature.
4.2.2.1 VLOOP Over-Current Protection
When VLOOP output is turned on, it is monitored for excessive current consumption caused by field
wiring or instrumentation problems. If sustained over-current is detected (100 ms), VLOOP is turned
off even though internal Digital Outputs 10 is turned on. This protection prevents unnecessary fuse
blowing, circuitry damage and rapid battery depletion.
When VLOOP output is turned on, using internal Digital Output 10, and a short circuit is detected
VLOOP will turn off. VLOOP will turn on to try again 5 seconds after turning off. If the fault
condition still exits VLOOP will again turn off and retry after a 5 second delay. While the fault
condition exists internal Digital Input 12 will be ON.
4.2.3 12V to 24V DC/DC Converter Control
The 12V to 24V DC/DC converter is used to provide 24 Vdc for VLOOP power and for the 5305
Analog Output module. The converter should be turned on if the SCADAPack LP is equipped with
analog outputs for which 24V drive capability is required. Otherwise, the DC/DC converter can be
turned off to conserve power.
• Turn on Digital Output 11 to turn ON the 12V to 24V DC/DC converter. When the converter is
turned on 24Vdc is provided to the VLOOP power and to the 5305 Analog Output module.
• Turn off Digital Output 11 to turn OFF the 12V to 24V DC/DC converter. When the converter
is turned off VLOOP power and the 5305 Analog Output module use is the applied input power.
Internal Digital Input 11 indicates the status of the 12V to 24V DC/DC converter. Digital Input 11
is set when the 12V to 24V DC/DC converter is on and is cleared when the 12V to 24V DC/DC
converter is off.
The 12V to 24V DC/DC converter is turned on when the LED power is enabled. This feature is
provided for service and diagnostics. Refer to section 11.3-LED Power Control for further
information on this feature
SCADAPack LP Hardware Manual
May 26, 2006
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