Omega Vehicle Security OM51 Application Notes Using the magnet, Simple application door monitor

Application Notes:
1) Using the magnet
You must orient the magnet to the case correctly for the
OM-51 State data logger to detect it. When the OM-51
State sees the magnet it will blink its green LED light.
When it cannot see the magnet it will blink its red LED
light. The recommended orientation (Diagram A), along
with some that will not work (Diagram B) are shown in	Diagram A
the drawings at the right.
	Diagram B

A simple application: door monitor

Mount the magnet on the door using its two-sided foam tape. Use the Window’s software to launch the logger, then mount the OM-51 State data logger on the door jam using the hook and loop strip. The magnet will need to be less than 1/4 inch from the logger case when the door is closed, and over 3/4 inch away when the door is open. Make sure that the logger blinks green when the door is closed, and red after it has been opened. The logger will record the times when the door is either closed or opened. The hook and loop tape allows you to conveniently remove and replace the logger for readout.

A door in a house, with small children living in it, recorded over one thousand state changes during a one week period in the summer!

2) Measuring contact closures

The OM-51 State can be used to measure contact closures. Connect the contacts to the black and white wires on the contact closure cable. The polarity of this connection does not matter. The red wire is not connected on the OM-51 State data logger. Using the external contact closure input allows the logger to be mounted remotely from the contact. Make sure that no external voltage is applied to the contacts! When measuring contact closures, the contacts should not be

Detailed Specifications:

Minimum state duration: 1/2 second

Time Accuracy: ±100 ppm at 20°C, full dependence shown in Plot A

Capacity: 2,000 state changes

External contact input: relay switch or contact closure

Length of included external contact cable: 6'

Operating temperature: -20°C to +70°C (-4°F to +158°F)

Relative humidity range 0 to 95%, non-condensing

Size/weight: 2.375" x 1.875" x 0.75"/approximately 1 oz.

Battery: CR-2032 (lithium); provides one year of continuous use

Storage temperature: -40°C to +75°C (-40°F to +167°F)

Connecting the communications cable

The OM-51 State data logger requires Logger Software and a PC interface cable. Connect the cable into the 3.5 mm jack on the logger (See diagram D) and into a working serial port of your computer. If the serial port was recently used for a network, modem, or printer, the port may still be configured as such and the computer should be restarted first. When attaching the PC interface cable to your logger, make sure that the interface cable is inserted completely into the jack on the logger.

Internal magnetic reed switch, external contact opening

The OM-51 State data logger records contact closures/openings of its internal magnetic reed switch (a glass reed switch located inside the box on the edge opposite the connectors, see Diagram E) and contact closures (open/shorted) in a cable connected to its 2.5 mm jack (Diagram D). The OM-51 State data logger detects the cable's open/shorted condition by applying a positive voltage pulse to the tip (white wire in cable). The black wire is ground and the red wire is not connected. Pairs of state changes that occur in less than half a second may not be recorded.

connected to anything else, even ground.

3) Measuring the presence of positive DC voltages

Put a diode in series with the white wire on the external contact closure cable. The diode will block the positive input. Note: it is critical that you connect the diode with the polarity shown in Diagram C. This will only work if the input voltage is ground when the positive voltage is not applied. Never apply a negative voltage to this input as the diode will not block it! Make sure you use a diode that has a breakdown voltage high enough to block the positive voltage you intend to apply. In no case should you use this technique to connect the logger to any AC

Operation indication

The OM-51 State data logger has two LED lights: red and green (Diagram D). One of these LEDs will blink every two seconds; if the contact is open the red LED will blink, if the contact is closed the green LED will blink. Although the LEDs blink every other second, the state is checked every half second, with state changes recorded as detected. If the battery voltage is low, both LEDs will blink every other second regardless of the state.

Battery

3.5mm jack

green

LED

red

LED

2.5mm jack

Magnetic

Diagram D Reed-switch Battery

location Holder

voltage, or a DC voltage above 15 volts.

white		diode
			voltage
contact closure cable
	black
to OM-51 State
		ground

Diagram C

Changing the battery Diagram E Diagram F

To change the battery, open the case as shown in Diagram E. Lift the circuit board and remove the battery by carefully pushing it out with a cotton swab with the tip removed or other small, blunt instrument. Be sure to install the battery with the printed side away from the OM-51’s cir- cuit board (Diagram F). The logger’s green LED will blink several times after the battery has been installed.

Keep it dry

Your OM-51 State data logger can be permanently damaged by corrosion if it gets wet. Protect it from rain or condensation. Should it get wet, remove the battery immediately and dry the board completely with a hair dryer before reinstalling the battery.

Data Format

The OM-51 State records the exact moment of each change of state. Current versions of the Windows software allow you to display this data in graphical or tabular format.