User's Guide

The Hardware View SB300 Series
Page 82 Proprietary and Confidential 2110059 Rev 1.0
Status Signal Interface
Status Outputs
There are three status outputs provided. These are active low and defined as follows:
1. \STATUS_OUT1: Power, RF Channel Status
• Permanently low (on) when power is on but no CDPD channel is visible. This
output is high (off) when the modem goes into logic sleep.
• Pulses low (on) once per second with 10% duty cycle if modem is locked onto a
CDPD channel.
• Pulses low (on) twice per second with 10% duty cycle if modem is registered on a
CDPD channel.
2. \STATUS_OUT2: Transmitter
• Low (on) when the transmitter is keyed.
3. \STATUS_OUT3: Power Down OK
• When low, (on) this indicates it is safe to remove power to the modem. This works in
concert with the \SHDN signal noted above.