User's Manual

HiLo3G-850 User Manual
04 March 2011 - Page 17 / 36
Figure 17: Complete V24 connection between the HiLo3G-850 and the host
This configuration allows the use flow control RTS & CTS to avoid any overflow error during data transfer. Also, CTS is
used to signal when the HiLo3G-850 is ready to receive an AT command after a power up sequence or a wake up from the
sleep mode.
Figure 18: C
In addition, this signal configuration enabled all signals :
• RI signal used when programmed to indicate an incoming voice or data call or SMS incoming message, etc.
• DCD signal used to signal the GPRS connections
• DSR signal used to signal that the module UART interface is ON
• DTR signal used to prevent the HiLo3G-850 from entering into the sleep mode, switching between Data and AT
commands, hanging up a call or waking up the module etc.
Pull-up resistors of 100KΩ to VGPIO must be connected to DCD, DSR and RI signals.
Avoid supplying the UART before the HiLo3G-850 is ON, this may result in power up sequence error.
3.5.2 Complete V24 Interface with PC
To use theV24 interface, some adaptation of components is necessary to convert the signals from the HiLo3G-850 to +/-
PWRON
CTS