User`s guide

2: BSC Protocol Summary
DC 900-1340I 41
called transmission blocks, to provide more accurate and efficient error control. BSC
begins each transmission block with a start-of-text (STX) control character and ends
each with an end-of-transmission-block (ETB) control character, except for the last
block of the message which ends with an end-of-text (ETX) character. All data blocking
and deblocking is transparent to the user; however, the ICP message buffer size
(Section 5.4.1.3 on page 119) and transmission block size (Section 6.8 on page 164)
must be defined by the user before a communication link is placed in operation.
2.3.5 BSC 2780/3780 Product Features
In addition to handling the basic BSC 2780 and BSC 3780 protocols, the Protogate
BSC 2780/3780 software includes several features that allow a user to tune the product
to handle protocol and programming variations. This manual describes these features
in detail in later sections.
The following features allow the user to adjust the product for variations of the
BSC 2780/3780 protocol:
• Signon procedure for exchange of local and remote identification sequences
• Safe store of received messages
• Selectable compression of spaces
• Selectable conversational mode
• Variable transmit text block size
• CRC-16 support for ASCII text blocks
• Variable reply timer and retry limit
• Selectable action on control characters (RVI, TTD, WACK, and ACK)
• Line turnaround control