Owner's Manual
Table Of Contents
Chapter 3 Optional Features and Accessories 29
Enable RS-232 port: When this option is off, it powers
down. When it is on, it powers up the RS-232 hardware. It
then displays the assigned COM port number.
Note: If you do not have a device plugged into the RS-
232 port, the port pins corrode more quickly when left
powered up. Use the setting to power down when it is not
going to be used.
Note: Power consumption during sleep is higher when the
RS-232 hardware is powered up.
Congure RS-232 Signals: Select Always enabled to
have the RS-232 output signals driving and input signals
enabled when the Mesa 3 is running or in sleep mode.
Select Disabled during sleep to have the RS-232 output
and input signals disabled automatically when the
tablet is in sleep mode. If your app and/or RS-232 device
experiences communication failures when tablet enters
or exits sleep mode, then do not use this option.
Congure pin 9 as input or 5 volt power supply: Pin 9 is the
Ring-In signal input. It is rarely used by devices anymore
and has become a popular pin to provide a power
source to an RS-232 device. Select Input if your device
uses Ring-In signal or if it does not need to be powered
from the RS-232 port. Select 5 Volt Power Supply to make
pin 9 a power supply to be used by the RS-232 device.
The power supply is enabled automatically without
needing any interaction with the COM port. Depending
on the model, the power supply is either 5 or 12 VDC.
The 12 VDC output option on RS-232 is always on and not
controlled by settings.
Turn on Disable power supply during sleep to cause the
power supply to automatically turn off when the tablet
is in sleep mode. This can allow the RS-232 device to
conserve battery power in sleep mode. If your app and/
or RS-232 device experiences communication failures
when the Mesa 3 enters or exits sleep mode, then leave
this option off.