Sierra Wireless DART 200 CDPD Modem - Manual (Page 99)

DART 200 CDPD Modem User’s Guide 8 Application Programming
PN1197-00 Revision 1.0 8-5
With three variables and only two signal lines, decide which two of
the three items are most crucial to the application. Usually, RF in
range and registration state are tracked. If both of these statuses are
present, then a Dial command (ATD) can be issued. To determine
more than two items of status the MAS escapes to command mode
and reads the network status register (S-Register 57).
• DTR (Data Terminal Ready) - Transitioning this signal lets the
application enter command mode without having to use the escape
sequence. To do this, the &D1
(escape) or &D2 (escape and
hang-up) option must be selected at initialization time. If this option
is used DTR must be held in the down state for a minimum of 15 ms.
Refer to Escaping through the control interface, p. 8-16, for more
information. The default is &D0 (ignore DTR)
• S-Register 56 (extended network error codes) - Indicates reasons for
a registration failure. Codes 1-7 are suggested in the CDPD
specifications but may not be followed by all carriers or
infrastructure providers.
1 Registration denied - Network Entity Identifier (NEI) may
be in use by another device
2 Service currently not available
3 Invalid NEI (IP Address)
4 Insufficient authentication credentials
5 Authentication credentials not supported
6 NEI has exceeded usage limitations
7 Service denied on this subnetwork; try an alternate Provider
250 Timed out waiting for home Mobile Data Intermediate
Station (MDIS) registration response
251 Mobile Data Link Protocol (MDLP) parameters unsupported
252 MDLP version unsupported
254 Could not access the CDPD network
255 Could not de-register the NEI because it was not registered
• S-Register 57 (network status) - A bit-mapped register showing
several items of interest. For error-handling the values of interest are:
• RF in range - value of 128 or greater (bit 7)
• Registered - odd value (bit 0)
• Connected - value of 133, 165, 197 or 229 (bit 2 and not bit 3)
• S-Register 62 (connection failure) - This register indicates at what
point in the operation the connection failed
1 During the connection process
2 During the transmission of a packet
3 During the reception of a packet
• S-Register 63 (connection failure) - This register indicates the most
probable cause for the connection failure or loss of connection
24 No socket available
67 Address already in use
69 Network is down