HEIDENHAIN iTNC 530 HSCI - Block Check Character (BCC); Communications Protocol with Block Check Character

1910 HEIDENHAIN Technical Manual iTNC 530 HSCI
10.8.3 Communications protocol with block check character
This protocol is specific to HEIDENHAIN and operates with its own control
characters and an additional data check feature when transmitting.
The protocol is set with the following operating modes:
 FE1 mode
 EXT1/EXT2/EXT3/EXT4 mode if MP5030.x = 1
The data transfer protocol is identical for all these modes except for the FE1
mode. In FE1 mode, a command sequence is output at the beginning to
request the contents directory from the peripheral device. For the FE1 mode,
bit 1 of MP5020.x must be set to 1.
Header When a file is transferred, the first block—called the header—consists of the
following characters:
<SOH><K><Name><M><ETB><BCC><DC1>
Block Check
Character (BCC)
In addition to checking the parity of the individual characters, the parity of the
complete transferred block is also checked. The BCC always rounds the
individual bits of the transferred characters in a data transfer block to even
parity.
Example of BCC generation:
In this example, program 15, which has been written in HEIDENHAIN plain-
language text (H), is input through the data interface (E).
A parity bit is also generated for the BCC. With even parity, the parity bit in this
example is assigned the value 1.
Character Meaning
<SOH> Identifies the beginning of the header
<K> File code
<Name> File name
<M> Data transfer mode (E = input, A = output)
<ETB> Identifies the end of the header
<BCC> Block Check Character
<DC1> XON
Character Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
SOH0000001
H 1001000
1 0110001
5 0110101
E 1000101
ETB 0010111
BCC0011111