Sierra Wireless DART 200 CDPD Modem manual Manual transmit control

DART 200 CDPD Modem User’s Guide 8 Application Programming

CAUTION: Automatic transmit control must be used with binary data since it is not dependent on data stream content.

Manual transmit control

This feature (AT\Mn) controls the recognition of data forwarding characters in the data stream by the packet assembler when in online mode. If enabled, the DART 200 recognizes the receipt of either of two data forwarding characters from the MAS as a condition to transmit the data in the packet buffer. Any data following the data forwarding character is not included in the current data packet, but is held over for the next transmission.

The \Fn command specifies whether or not either, or both, of the data forwarding characters are included in the data packet. These characters are specified in S-Registers 51 and 52. The default value for S-Register

51is 13 <CR>, and for S-Register 52 is 26 <SUB>; these values can be changed by the end-user. The default for \Fn is \F3; include both characters in the packet.

If manual transmit control is disabled, the data forwarding characters are included in the data packet regardless of the setting of the \Fn command.

The DART 200 factory default is Manual Transmit Control disabled (\M0).

Automatic transmit control

This feature controls the use of the inter-character time-out data forwarding operation of the packet assembler when in online mode. The inter-character timer determines the amount of time (idle time) allowed between characters received from the MAS. The time out value is specified in S-Register 50 in 1/10 second increments; the default value is 20 (2 seconds). For optimum performance set this value as small as possible, values of 1 (100 ms) or 2 (200 ms) are commonly used

The time-out period can be viewed as either the maximum time permitted between two characters for them to appear in the same packet, or the wait time after the last character is put in the buffer until the packet is transmitted. Automatic transmit control must be used with binary data since it is not dependent on data stream content.

This feature is controlled by the AT\Tn command. The DART 200 factory default is Automatic Transmit Control enabled (\T1).

PN1197-00 Revision 1.0 8-9