Data Sheet

Smart Machine Smart Decision
serial interface.
The default flow control approach of SIM800 Series is hardware flow control (RTS/CTS flow
control), to enable software flow control in the DTE interface and within GSM engine, type the
following AT Command:
AT+IFC=1, 1
This setting is stored volatile, for use after restart, AT+IFC=1, 1 should be stored to the user
profile with AT&W.
NOTE:
The AT commands listed in the table of AT&W chapter should be stored to user profile with
AT&W for use after restart. Most other AT commands in V.25, 3GPP TS 27.005, 3GPP TS
27.007,GPRS will store parameters automatically and can be used after module restart.
Ensure that any communications software package (e.g. Hyper terminal) uses software flow
control.
NOTE:
Software Flow control should not be used for data calls where binary data will be transmitted or
received (e.g. TCP/IP) as the DTE interface may interpret binary data as flow control characters.
1.6.2 Hardware flow control (RTS/CTS flow control)
Hardware flow control achieves the data flow control by controlling the RTS/CTS line. When the
data transfer should be suspended, the CTS line is set inactive until the transfer from the
receiving buffer has completed. When the receiving buffer is ok to receive more data, CTS goes
active once again.
To achieve hardware flow control, ensure that the RTS/CTS lines are present on your application
platform.
1.7 Definitions
1.7.1 Parameter Saving Mode
For the purposes of the present document, the following syntactical definitions apply:
z NO_SAVE: The parameter of the current AT command will be lost if module is rebooted or
current AT command doesn't have parameter.
z AUTO_SAVE: The parameter of the current AT command will be kept in NVRAM
automatically, and it won't be lost if module is rebooted.
z AT&W_SAVE: The parameter of the current AT command will be kept in NVRAM by
sending the command of “AT&W.”
SIM800 Series_AT Command Manual_V1.05 24 2014-07-31