Bcc Calculation Example; Response Frame - Omron KM50 Communications Manual

■ BCC Calculation Example

The BCC (Block Check Character) is determined by finding the exclusive OR of the bytes from the
node number through the ETX. The 8-bit result is written to the BCC byte at the end of the frame.

■ Response Frame

Node No.
STX
1 2
End code Name
00 Normal completion
FINS command
0F
error
10 Parity error
11 Framing error
12 Overrun error
13 BCC error
14 Format error
Frame length
18
error
• An end code is returned for each command frame received by the addressed node.
• No response will be returned unless the command frame contains all elements up to the ETX
and BCC.
• The "error detection priority" indicates the priority when two or more errors occur simultaneously.
Sub-address End code
2 2
The command ended normally without error.
The specified FINS command could not be executed.
The FINS response code should indicate why the command
could not be executed.
The sum total of "1" bits in the received data does not match
the set value of the communications parity bit.
The stop bit is 0.
An attempt was made to transfer new data when the
reception data buffer was already full.
The calculated BCC value is different from the received BCC
value.
• The command text contains characters other than 0 to 9
and A to F. This error does not apply to echoback tests.
(Refer to Echoback Test for details.)
• There was no SID and command text. There was no
command text.
• The MRC/SRC was not included in command text.
The received frame exceeds the specified (supported)
number of bytes.
Command text
Description
2. 1 Data Formats
BCC
ETX
1 1
Error
detection
priority
None
7
2
1
3
6
5
4
2-3