Hardware Flow Control (Rts/Cts Flow Control); Unsolicited Result Code - Quectel M35 Command Manual

GSM/GPRS Module
M35 AT Commands Manual

1.4.2. Hardware Flow Control (RTS/CTS Flow Control)

to enable hardware flow control (RTS/CTS flow
The default flow control approach of M3 is closed,
control) in the DTE interface and within GSM engine, type the following AT command:
AT+IFC=2, 2<CR>.
This setting is stored volatile, for use after restart, AT+IFC=2, 2<CR> should be stored to the user profile
with AT&W<CR>.
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.

1.5. Unsolicited Result Code

A URC is a report message sent from the ME to the TE. An unsolicited result code can either be delivered
automatically when an event occurs, to reflect change in system state or as a result of a query the ME
received before, often due to occurrences of errors in executing the queries. However, a URC is not
issued as a direct response to an executed AT command. AT commands have their own implementations
to validate inputs such as "OK" or "ERROR".
Typical URCs may be information about incoming calls, received SMS, changing temperature, status of
the battery etc. A summary of URCs is listed in Appendix A.
When sending a URC, the ME activates its Ring Interrupt (Logic "l"), i.e. the line goes active low for a few
milliseconds. If an event which delivers a URC coincides with the execution of an AT command, the URC
will be output after command execution has completed.
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