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9.   Application Examples



9.1.   Monitoring Signal Drop and/or Power Loss

In this application, the PLS-345 will monitor the DTR signal from a data device. If the signal drops or the data device loses power for more than one minute, the unit will automatically switch circuits 2 and 3 to the "B" line.

Monitoring Signal Drop
Figure 9.1:   Monitoring Signal Drop

  1. Connect Line from Data Device:  Connect a line from the Data Device to the Monitor Input Connector as shown in Figure 9.1.


  2. Set Monitor Selector Switch:  Locate the Monitor Selector Switch on the PLS back panel. Slide the switch to the "RS232" position.


AUX Port Connection
Figure 9.2:   AUX Port Connection

  1. Configure Monitor Mode:  Access the PLS command mode as described in Section 5.2. At the PLS> command prompt, type /M [Enter] to display the Monitor Mode Parameters Menu. Note that the Monitor Mode Parameters Menu is not available in User Mode. Set Monitor Mode Parameters as follows:


    1. Item 1 - Monitor Mode:  On.


Note:  Do not enable the Monitor Mode until you have finished defining the other Monitor Mode parameters.
    1. Item 2 - Switch if Level:  0 - Low.


    2. Item 3 - Switch to Position:  B.


    3. Item 4 - Delay Period:  1 Minute.


    4. Item 5 - Return:  Off (Note that if you wanted the A/B circuits to return to their original positions if the monitored line goes high again, then this item would be enabled.)


    5. Item 6 - Circuits to Switch:  Enable the Monitor Mode at circuits 2 and 3.


  1. Set Circuit Parameters:  From the PLS command prompt, type /P 2 [Enter] to display the Circuit 2 Parameters Menu. Use item 4 (Default Position) in the Circuit Parameters Menu to set the default state for Circuit 2 to "A". Repeat this procedure for Circuit 3 (use the /P 3 command to access the Circuit 3 Parameters Menu.)


  2. Operation:  When the DTR signal is present (high), Circuits 2 and 3 will remain in the default (A) position. If the DTR drops for more than one minute, PLS A/B Circuits 2 and 3 will be switched to the "B" position.


9.2.   Monitoring a Contact

In this application, the PLS will monitor a switch or contact. When the contact closes (signal goes low) for more than one minute, the PLS will automatically switch module 1 to the "B" position. Later, if the contact returns to the open position, the PLS will return circuit 1 to the "A" position.

Monitoring a Switch or Relay
Figure 9.3:   Monitoring a Switch or Relay

Note:  This example could also be used to monitor a contact or switch that is normally closed. To automatically switch A/B circuits when a contact is opened, use item 3 (Switch if Level) in the Monitor Mode Parameters Menu (Section 5.7.2) to select the "1 - High" option.
  1. Connect Line from Data Device:  Connect a line from the contact to the Monitor Input Connector as shown in Figure 9.3.


  2. Set Monitor Selector Switch:  Locate the Monitor Selector Switch on the PLS back panel. Slide the switch to the "CONTACT" position.


AUX Port Connection
Figure 9.4:   AUX Port Connection

  1. Configure Monitor Mode:  Access the PLS command mode as described in Section 5.2. At the PLS> command prompt, type /M [Enter] to display the Monitor Mode Parameters Menu. Note that the Monitor Mode Parameters Menu is not available in User Mode. Set Monitor Mode Parameters as follows:


    1. Item 1 - Monitor Mode:  On.


Note:  Do not enable the Monitor Mode until you have finished defining the other Monitor Mode parameters.
    1. Item 2 - Switch if Level:  0 - Low.


    2. Item 3 - Switch to Position:  B.


    3. Item 4 - Delay Period:  1 Minute.


    4. Item 5 - Return:  On (This will instruct the PLS to switch Circuit 1 back to the "A" position if the signal goes high again, and remains high for one minute.)


    5. Item 6 - Circuits to Switch:  Enable the Monitor Mode at circuit 1.


  1. Set Circuit Parameters:  From the PLS command prompt, type /P 1 [Enter] to display the Circuit 1 Parameters Menu. Use item 4 (Default Position) in the Circuit Parameters Menu to set the default state for Circuit 2 to "A".


  2. Operation:  When the switch is open, the input level will remain high, and Circuit 1 will remain in the "A" position. If the switch closes for more than one minute, the input level will drop, and Circuit 1 will be automatically switched to the "B" position. If the switch returns to the open position, and remains open for one minute, then Circuit 1 will return to the "A" position.