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SIM800 Series_AT Command Manual_V1.09

2015-08-03

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:



NO_SAVE: The parameter of the current AT command will be lost if module is rebooted or

current AT command doesn't have parameter.



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.



AT&W_SAVE: The parameter of the current AT command will be kept in NVRAM by

sending the command of “AT&W.”

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