Application Note AN100

How to configure networked eCNA automationsto use a single LVM-250 Voltage Monitor using Virtual I/O

Introduction

The LVM-250 Voltage Monitor is used in conjunction with the eCNA to monitor the power line for avoltage sag or a voltage loss. The LVM-250 sends the measured RMS line voltage to the eCNA via theLIN serial link. The eCNA monitors this voltage and based on user defined parameters generate eventsthat can be used to stop or pause the SMS and other equipment in the event of an under voltagecondition.

Using the LVM-250 with the eCNA automation assumes the booth equipment (including the network)is back-up powered by an Uninterruptable Power Supply (UPS). In the event of a power line voltageloss, the equipment should be automatically shut down in a controlled manner. There are a couple ofways to use the LVM-250 to monitor the power line in the booth. You can use one at each screen tomonitor the power line at each distribution panel or use one LVM-250 to monitor the power line for theentire booth. This application note describes the latter. However, you can apply the same concepts toimplement the former.

Networked eCNAs can use Virtual I/O to control and monitor line voltage events. Virtual I/O consistsof 16 user-defined I/O control flags that can be used by any eCNA on the Ethernet network that arepart of the same Multicast Group. An LVM-250 can be connected to any one of the eCNAs. This eCNAis configured to control virtual output control flags based on line voltage events. All other eCNAs areconfigured to monitor these flags. For the purposes of this application note, the eCNA that isconnected to the LVM-250 is referred to as the Master. All other eCNAs are Slaves. The eCNAs mustbe running firmware version 1.130 or later.

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Example

If the line voltage drops below 185 volts, a 10 second timer starts. If the voltage goes above 190 voltsbefore the 10 second timer expires, the timer is reset and the SMS will continue to play. If the voltagestays below 185 volts for longer than 10 seconds, the SMS will be paused. If the voltage is restored(above 190 volts) before 1 minute, the SMS is restarted if the voltage is okay for 5 seconds. If thevoltage is restored after 1 minute, the SMS remains paused. This example uses Line Voltage Low, LineVoltage OK 1 and Line Voltage OK 2 events to implement this control.

1 Setting up the eCNA Master

The following configuration is required at the master.

• Setup LVM-250 Parameters• Setup Control Flag Names• Setup Virtual I/O• Setup Macros• Setup Triggers

1.1 Setup LVM-250 Parameters

Configure the LVM-250 parameters as shown. Voltage logging is optional.

Parameter Name Symbol Definition

Lower Voltage Threshold VTL Establishes the low voltage trip point. Range = 0 to 250 volts

Upper Voltage Threshold VTU Establishes the upper voltage okay point. Range = 0 to 250 volts

Voltage Low Event Hold-Off Time TVLH Sets the delay from the line voltage not okay condition to the Line Voltage LowEvent. Range = 0:00 to 59:59 mm:ss

Voltage Low Window Time TVLW Establishes a time period where the Voltage OK 1 Event can occur. Range = 0:00to 59:59 mm:ss

Voltage OK Event Hold-Off Time TVOH Sets the delay from the from the line voltage okay condition to the Line Voltage OK1 and OK 2 Events. Range = 0:00 to 59:59 mm:ss

Voltage Logging Period Sets the Voltage Logging interval. Range = 0:00 to 59:59 mm:ss. 0:00 disableslogging.

Voltage Logging Lower Threshold Logs readings only below this threshold

Voltage Logging Upper Threshold Logs readings only above this threshold

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The three Line Voltage events that are used as triggers are described below.

Line Voltage Low - This event occurs when the line voltage goes below the ‘Lower VoltageThreshold’, VTL for a time greater than the ‘Voltage Low Event Hold-Off Time’, TVLH.

Line Voltage OK 1 - This event can only occur inside the ‘Voltage Low Window’. This event occurswhen the line voltage returns to the okay condition and remains okay for a time greater than the‘Voltage OK Event Hold-Off Time’, TVOH.

Line Voltage OK 2 - This event can only occur outside the ‘Voltage Low Window’. This eventoccurs when the line voltage returns to the okay condition and remains okay for a time greaterthan the ‘Voltage OK Event Hold-Off Time’, TVOH.

This diagram illustrates how the Line Voltage events are generated. The red line represents the linevoltage (RMS value). When the voltage drops below the Lower Voltage Threshold, VTL, the VoltageLow Hold-off, TVLH, and the Voltage Low Window, TVLW, timers start to tick. If the Voltage Low Hold-off timer, TVLH, is allowed to expire, the Line Voltage Low Event is generated. If the voltage goesabove the Upper Voltage Threshold, VTU, before the Voltage Low Window timer, TVLW, expires, theVoltage Okay Hold-off timer, TVOH, starts to tick. If this timer is allowed to expire, the Line VoltageOK 1 Event is generated. If the voltage goes above the Upper Voltage Threshold, VTU, after theVoltage Low Window timer, TVLW, expires, the Voltage Okay Hold-off timer, TVOH, starts to tick. Ifthis timer is allowed to expire, the Line Voltage OK 2 Event is generated.

1. The Voltage Low Hold-off timer, TVLH, is reset if the voltage goes above the Upper VoltageThreshold, VTU and the Line Voltage Low event will not be generated.

2. The Voltage Okay Hold-off timer, TVOH, is reset if the voltage falls below the Lower VoltageThreshold, VTL, and the Line Voltage OK 1 or the Line Voltage OK 2 event will not begenerated.

3. The Voltage Low Window timer, TVLW, is reset if the voltage goes above the Upper VoltageThreshold, VTU.

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1.2 Setup Control Flag Names

Out 1, Out 2 and Out 3 control flags will be configured as virtual outputs controlled by the LineVoltage events. These will be used by all other eCNAs on the network.

Out 4 will be used as the Voltage Monitoring (VM) control flag. If the voltage returns to the okaycondition after 1 minute, the VM flag is set. This prevents the SMS from restarting if the voltage isrestored. The flag must be cleared so the eCNA is ready to sense the next power outage. Thisshould happen on a start or resume by setting Out 4 to Off with an output command or a macro.

1.3 Setup Virtual I/O

Assign these output flags to the Virtual I/O output bits as follows. VOut 1 is configured forMaintained so that any Slave that joins the group can detect the under voltage condition. VOut 2and VOut 3 are configured for Pulsed.

1.4 Setup Macros

In order to keep these macros simple for this example, we are only controlling the start and pauseof the SMS. In a practical application, you may need to control other devices such as the projector,sound processor and lights. These macros CAI SendF1 to start the SMS and SendF2 to pause theSMS. Assign names to these two message in the CAI SendFx Names screen.

Macro 1: The SMS Start macro starts the SMS and clears the Voltage Monitor flag if the LineVoltage Low flag is not set. This macro can be started from an input, a key press or a commandfrom a CAI client. The ‘Exit If’ instruction prevents the eCNA from sending the Start SMS commandin an “under voltage” condition.

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Macro 2: The SMS Pause/Stop macro is executed when the Line Voltage Low event pauses theSMS (if the VM flag has not been set).

Macro 3: The Set VM Flag macro sets the Voltage Monitoring (VM) flag. This macro is executed ifthe “Voltage OK 2" event occurs preventing the eCNA from sending the Start SMS command toresume the playlist. The second instruction causes the “Voltage OK 2" event to be sent to othereCNAs.

Macro 4: The Auto Resume macro resumes the SMS only if the Voltage Monitoring (VM) flag iscleared. Aux Out 2 is placed before the ‘Exit If’ instruction so the Voltage OK 1 output is alwayssent to other eCNAs regardless of the state of the VM Flag.

1.5 Setup Triggers

Assign the triggers as follows.

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2 Setting up the eCNA Slaves

Slaves are configured to monitor the Virtual output flags controlled by the master eCNA. Since theslaves are not looking at the Line Voltage events, you can disable the LVM-250 on all slaves.

The following configuration is required at each of the slaves.

• Setup Control Flag Names• Setup Virtual I/O• Setup Macros• Setup Triggers

2.1 Setup Control Flag Names

In 1, In 2 and In 3 control flags will be used as virtual inputs to monitor the Line Voltage eventscontrolled by the master eCNA.

Just as in the master eCNA, Out 4 will be used as the Voltage Monitoring (VM) control flag for thesame purpose. Again, if the voltage returns to the okay condition after 1 minute, the VM flag is set.This prevents the SMS from restarting if the voltage is restored. The flag must be cleared so theeCNA is ready to sense the next power outage. This should happen on a start or resume by settingOut 4 to Off with an output command or a macro.

2.2 Setup Virtual I/O

Assign the input flags to the Virtual I/O input bits as follows.

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2.3 Setup Macros

Macro 1: The SMS Start macro starts the SMS and clears the Voltage Monitor flag. This macro canbe started from an input, a keypress or a command from a CAI client.

Macro 2: The SMS Pause/Stop macro is executed when the Line Voltage Low event pauses theSMS (if the VM flag has not been set).

Macro 3: The Set VM Flag macro sets the Voltage Monitoring (VM) flag. This macro is executed ifthe “Voltage OK 2" event occurs preventing the eCNA from sending the Start SMS command toresume the playlist.

Macro 4: The Auto Resume macro resumes the SMS (only if the VM flag is cleared).

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2.4 Setup Triggers

Assign the triggers as follows. These are similar to the master eCNA, except that the events arecaused by the virtual inputs.

Testing

Start the test by running macro 1 at all eCNAs to start the SMS playlist. Remove the line voltage fromthe LVM-250. If you wait more than 10 seconds the SMS will be paused. If you restore the voltagebefore the 1 minute Voltage Low Window Time, the SMS playlist will resume.

Conclusion

This is just one of many ways to use the Line Voltage events to automatically control the boothequipment on a line voltage fault using Virtual I/O. Virtual I/O can be used for control purposes forother “global” events such as a building fire alarm. See Application Note AN101.

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