USR-GPRS232-730 User Manual
Jinan USR IOT Technology Limited
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4. Parameters Setting
4.1. AT commands Set
4.1.1. AT command Mode
When USR-GPRS232-730 works in one of the three modes: SMS message transmission, network
transmission mode or HTTPD mode. You can get module into “command mode” by sending specific timing
data to it, then send commands to change module’s running parameters. If changing is done, get module back
to previous work mode.
In the above figure, abscissa axis means time, the data above time axis is sent to module from device,
and the data bellow time axis is sent to device from module.
Time requirement
T1 > 200ms
T2 < 50ms
T3 < 50ms
T5 < 3s
Get into command mode:
1) Module is in SMS message transmission, network transmission or HTTPD mode.
2) Device send “+++” to module, then module send ‘a’ to device.
3) If device receives ‘a’, it must send ‘a’ to module within 3 seconds.
4) Module receives ‘a’, and sends “+ok” to device.
5) Device receives “+ok”, it means module has gone to temporary command mode, so device can send
AT commands to module.
Back to previous mode:
1) Device send command “AT+ENTM” to module.
T7
T5
T1
T2
T4
T3
T6
Sending data to device
TIME
+
Sending data to module
+
+
a
a
+ok
AT+ENTM
OK
