User`s guide

4: BSC 3270 Link Configuration Options
DC 900-1340I 99
then deblocks the message such that the 3270 command strings are not split across
transmission block boundaries.
4.18 Block Checking Option (20)
This option determines what characters are included in the block check character
(BCC) calculation on transmitted and received data blocks. If the received block check
character does not match the BCC value calculated by BSC, the
DLI_ICP_ERR_BAD_BCC
error code is returned to the client application. Block checking can be set to include or
exclude the leading BSC control character or can be disabled completely.
If the option is set to exclude, the BCC calculation starts with the first data character fol-
lowing STX. This is the normal BSC mode of BCC calculation.
If the option is set to include, the STX is included in the BCC calculation for transmitted
and received data blocks.
If the option is set to disable, a block check character is still generated on transmit and
expected on receive, but the receive BCC comparison is not performed and each
received data block is sent to the client without regard to any possible error. The BCC
calculation is done on transmitted blocks as if the option is set to exclude.
To set this option using the DLI configuration file, use the blockChecking parameter; for
example,
blockChecking = “exclFirst”. See Table 7–1 on page 190.
Note
When transmitting non-transparent text, embedded SYN charac-
ters are not included in the outbound BCC calculation.