Home WTI User's Guides
1. Introduction
2. Binary Block Read Mode and Structure
2.1. Compressed Binary Block Read Sequence
2.2. Compressed Binary Block Structure
2.2.1. Data Block Structure
2.2.2. Record String Structure
3. Compression Decompression Methods
3.1. Table Decompression
3.1.1. Nibble Positioning
3.1.2. Record String Format Data Decompression Considerations
3.1.3. Table Decompression Example
3.2. Space Compression
4. DLE Stuffing
5. The Cyclic Redundancy Check Option
5.1. Calculation
6. Customer Service
PollCat Series

2.2.1. Data Block Structure


As shown in Figure 2, the Data Block includes the following items:



Figure 2: Data Block Structure

Block Header: The Block Header has three components:

1. Block Number (optional): A two byte binary block number similar to the line number in the line-by-line mode. The Block Number component is selected by enabling the Line

I.D. Option (^B59,2).

2. Block Type Byte: This byte tells the polling device what kind of block is being transmitted. The byte settings and corresponding block types are listed below:

•                      "00" data record block.

•                      "A1" alarm record block.

•                      "FF" end block, not a call record block but a block containing the data "END DATA".

•                      "FE" binary info block.


3. Record Count Bytes "NREC": A two byte, binary count of the number of call records in the block.

Record Strings: Each Record String contains a Record Header and Compressed Binary Data as described in Section 2.2.2.