TApxProtocol.BlockCheck

TApxProtocol

property BlockCheckMethod : TApxBlockCheckMethod
TApxBlockCheckMethod = (
bcmNone, bcmChecksum, bcmChecksum2,
bcmCrc16, bcmCrc32, bcmCrcK);

Determines the error checking method used by the protocol.

The default error checking method depends on the protocol. See the section describing each protocol at the beginning of this chapter for additional information.

The following values can be assigned to the property:

Value
Description
bcmNone
No error checking
bcmChecksum
Single byte checksum
bcmChecksum2
Two byte checksum used by Kermit
bcmCrc16
16-bit CRC
bcmCrc32
32-bit CRC used by Zmodem
bcmCrcK
Three byte CRC used by Kermit 

The Xmodem1K, Xmodem1KG, Ymodem, YmodemG, and ASCII protocols provide either no error checking or a single error checking mode, so they ignore assignments to BlockCheckMethod.

Assigning bcmCrc16 to BlockCheckMethod converts an Xmodem protocol into an XmodemCrc protocol. Conversely, assigning bcmCheckSum to BlockCheckMethod converts an XmodemCrc protocol to an Xmodem protocol.

The Zmodem protocol accepts only the bcmCrc16 and bcmCrc32 types. The Kermit protocol accepts only the bcmChecksum, bcmCheckSum2, and bcmCrcK types.

No error is generated if an unaccepted type is assigned, but the assignment is ignored. You should be sure to set the desired ProtocolType before setting a non-default BlockCheckMethod.

See also: ProtocolType