Vloop Power Control; To 24V Dc/Dc Converter Control - Control Microsystems SCADAPack 350 Hardware Manual

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When the LED power is disabled, HMI power is turned on for five minutes when a momentary
contact is made between pin 2 (DCD) and pin 3 (DTR) on the RJ-45 connector of COM3. This
permits the SCADAPack Vision or an HMI pushbutton to control HMI power. At each
momentary contact, the five-minute power timer is reloaded. If the five-minute power timer is
maintaining the HMI power on, a momentary contact between DCD and DTR will turn off HMI
power. Refer to section 10.1.4.2-RJ-45 to SCADAPack Vision for more information.
Internal Digital Input 12 indicates the status of COM3 serial port power. Digital Input 12 is set
when COM3 serial port power is on and is cleared when COM3 serial port power is off.
HMI power is turned on whenever the LED power is enabled. This feature is provided for service
and diagnostics. Refer to section 13.3-LED Power Control for further information on this feature.
4.4.2

VLOOP Power Control

The DC/DC converter output can be used to power analog input current loops or other
instrumentation. This output, VLOOP, is controlled for intermittent or continuous operation. Turning
the VLOOP output off when it is not required can save considerable electrical power.
The switched VLOOP power source is the output of the DC-DC 12/24V converter if it is turned on.
See section 4.4.3- 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.
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Turn on Digital Output 8 to turn ON the VLOOP output.
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Turn off Digital Output 8 to turn OFF the VLOOP output.
Internal Digital Input 8 indicates the status of VLOOP power. Digital Input 8 is set when VLOOP
power is on and is cleared when VLOOP power is off.
When VLOOP is first turned on, the user application program must wait some period of time
Note:
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 13.3-LED Power Control for further information on this feature.
4.4.2.1 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 10 will be ON.
4.4.3 12V to 24V DC/DC Converter Control
The 12V to 24V DC/DC converter is used to provide 24V DC for VLOOP power and for the 5305
Analog Output module. The converter should be turned on if the SCADAPack 350 is equipped with
analog outputs for which 24V drive capability is required. Otherwise, the DC/DC converter can be
turned off to conserve power.
SCADAPack 350 Hardware Manual
February 14, 2007
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