Omron C-series manual Backup Power Supply, Example, Using the Auxiliary Power Input Terminal

	Backup Power Supply	Section 2-5
		When total transmission loss from the system is subtracted from the transmit/re-
		ceive differential of the Link Adapters, the margin must be at least 4 dB. To deter-
		mine total transmission loss, first calculate the loss over the cable by multiplying
		the loss/km by the total length of the cable. Then calculate the loss at the con-
		nections by multiplying the loss/connection by the number of connections. Final-
		ly, add the cable loss and the connector loss. Subtract this figure, the total trans-
		mission loss, from the transmit/receive differential. If the difference is greater
		than 4 dB, then the cable length is acceptable.
Example 1		Distance: 2.5 km; Connecting points: 4; Connecting method: permanent

	When this total transmission loss of 7.9 dB is subtracted from the 13 dB transmit/
	receive differential of the Link Adapters, it leaves a margin of 5.1 dB. The 13 dB
	includes all loss at the Link Adapter connectors.
Example 2	Distance: 2 km; Connecting points: 3; Connecting method: connectors

When this total transmission loss of 8.1 dB is subtracted from the 13 dB transmit/ receive differential of the Link Adapters, it leaves a margin of 4.9 dB, safely above the minimum margin of 4 dB.

2-5 Backup Power Supply

Using the Auxiliary Power Input Terminal

Link Adapters which depend on a power supply (i.e., all except the AL001) are unable to transmit signals when power is cut off. Link Adapters AL002-(P)E, AL005-(P)E, and AL006-(P)E, however, have auxiliary power input terminals which can be connected to a battery to ensure continued operation even when the AC power supply is cut off.

Only the three Link Adapters listed above have this terminal. They can operate on a low voltage (12-24 VAC/DC) power supply in place of their normal power supply of 100/200 VAC. When it is necessary to have a backup power supply, connect a 12V battery to this terminal. If the battery is left unused for a long peri- od it will discharge. It must either be periodically charged or connected to a float- ing charging device. To avoid overcharging, set the output voltage at 13V. Do not use a 24V battery.

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