User`s guide

88 DC 900-1339H
FMP Programmer’s Guide
4.13.5 Raw Blocks with Header
On inbound messages with Message Blocking set to Raw Blocks with Header, FMP strips
any leading PAD or SYN characters and trailing PAD characters from the message. The
message is sent to the client with all BSC control characters and BCC characters present.
This is the same format as in the Raw Blocks setting except that each block is preceded
by a 5-byte header that contains information about the block (see Appendix C for the
error code values). Figure 4–12 on page 87 shows the format of the record header. The
first two bytes contain a 16-bit count of the number of bytes that follow it (including the
rest of the block header). The next two bytes contain a 16-bit FMP-generated block
sequence number. The last header byte contains an 8-bit error code pertaining to that
block. If the block contains no errors, this field is zero. If a BCC error or other receive
error is detected in any record within the block, an error code is placed in this field.
Figure 4–14 is an example of the Raw Blocks with Header setting using the sample
received data blocks shown in Figure 4–6 on page 82.
On outbound messages, the client application places all the control characters (except
SYN and PAD) into the block before sending it to Freeway (as in the Raw Blocks setting).
Figure 4–13: Message Blocking Example (Data Records with Header)
06 00 0
A B C
Message Blocking = Data Records (With Header)
Data Packing = Disabled
06 01 0
D E F
06 02 0
G H I
06 02 0
J K L
3268
Note 5-byte header in this example = 06 00 0
Where: 06 = size of record including seq # and error code
00 = Simpact generated sequence number of block
0 = error code for record