Transmit binary data

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Line endings

Note that RockBLOCK expects commands to be terminated with a carriage return (\r) character. This is hex 0x0D.

Using a line-feed (\n) hex 0x0A character will not work!

With your RockBLOCK connected to a suitable power supply, check that your serial communications are established (default 19200, 8N1) and issue the commands:

/* Issue AT command */

AT\r

/* Receive response */

OK\r

/* Turn off Flow Control */

AT&K0\r

/* Receive response */

OK\r

/* Define binary message length in MO buffer not including the mandatory 2 Byte checksum*/

AT+SBDWB=[<SBD Message Length>]\r

/* Receive response */

READY\r

/* Stream binary message and 2 byte checksum.*/

<Binary Message>+<Checksum>\r

/* Receive Response */

<Status>\r

OK\r

/* Initiate an Extended SBD Session */

AT+SBDIX\r

/* Receive response */ 

+SBDIX: <MO status>, <MOMSN>, <MT status>, <MTMSN>, <MT length>, <MT queued>\r

/* See SBDIX Key for information on each parameter */

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Check SBDWB status

Before initiating an SBD session, make sure your SBDWB status is 0.

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SBDWB Key

<Status>
0 - SBD message successfully written to the ISU.
1 - SBD message write timeout. An insufficient number of bytes were transferred to ISU during
the transfer period of 60 seconds.
2 - SBD message checksum sent from DTE does not match the checksum calculated at the ISU.
3 - SBD message size is not correct. The maximum mobile originated SBD message length is 340 bytes. The minimum mobile originated SBD message length is 1 byte.

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SBDIX Key

The SBDIX command denotes the status of your sent, received and queued messages:

<MO status> - Any returned number with a value of 0 to 2 indicates your message has been successfully transmitted. Any number above 2 indicates that the message has not been successfully transmitted.

<MOMSN> - This number denotes the MO message number and cycles between 0 and 65535.

<MT status>
0 - No messages waiting to be received.
1 - New message successfully received.
2 - Error during mailbox check / message reception.

<MTMSN> - This number denotes the MT message number and cycles between 0 and 65535.

<MT length> - The size (in bytes) of the MT message.

<MT queued> - The number of MT messages in the queue waiting to be downloaded.

An SBDIX response of 0,0,0,0,0,0 indicates that a message was transmitted successfully, that there were no MT messages downloaded during this SBD session and that no messages are waiting in the queue to be downloaded.

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Further information on AT commands

Please refer to the Iridium ISU AT Command Reference for more information on the available AT commands.

After sending a message using SBDWB followed by a successful SBDIX, we recommend clearing the MO buffer with the command SBDD=0. If you don't clear the MO buffer, and also don't overwrite it with a new MO message, the modem will try to re-send this same message in the next transmission. Clearing the MO buffer is necessary if you're alternating between sending/not sending MO messages.

AT commands in this chapter

+SBDWB
+SBDIX[A]