Black Channel: General Black Channel type 1 - Point-to-Point¶
Overview¶
The GBC1 (General Black Channel type #1) implements a point-point duplex protocol between two simplifiers. The simplifier uses uart communication, to send fixed size packets to the other end. The protocol is completely symmetrical, there is no master/slave. Timestamps are incoporated in the packet, and the round-trip time is measured accurately. This round-trip is used as worst case estimation of one way delay.
Tables¶
The black channel fulfills 61508-2 and 61784-3:2021, justified in this document, together with the RER calculations.
error type |
mitigation |
PASS |
Reference |
|---|---|---|---|
transmission errors |
Protected by 24-bit CRC and part of Chaskey hash. |
TRUE |
|
repetitions |
protected by timestamp. |
TRUE |
|
deletion |
As there is no state in the data, just update, deletion is not critical |
TRUE |
|
insertion |
protected by timestamp. |
TRUE |
|
re-sequencing |
protected by timestamp. |
TRUE |
|
corruption |
Protected by 32-bit CRC and part of Chaskey hash |
TRUE |
|
delay |
round trip is measured and used as worst case delay |
TRUE |
|
masquerade |
Simplifiers unique serial number is used to make sure the correct units talk with each other |
TRUE |
Verification |
mitigation |
Pass |
Reference |
|---|---|---|---|
D.4.3 ”De-Energize to trip” |
A communication timeout is implemented for receiving end, the result will internall be 0 and invalid will be 1. |
TRUE |
|
D.4.4 ”Safe state” |
Loss of packets sets all signals to ”OFF”, which is safe state for them. Also, the invalid state is set. |
TRUE |
|
D.4.5 ”Transmission errors” |
CRC mismatch is handled as lost packet. |
TRUE |
|
D.4.6 ”Safey reaction and response times” |
The communication timeout is configured according to the application requirements |
TRUE |
error type |
mitigation |
PASS |
Reference |
|---|---|---|---|
5.4.2 Sequence number |
timestamp is used |
TRUE |
|
5.4.3 Time Stamp |
timestamp is used |
TRUE |
|
5.4.4 Time expectation |
round trip is measured and timestamp information is used to verify expectation |
TRUE |
|
5.4.5 Connectin authentication |
Simplifiers unique serial number is used |
TRUE |
|
5.4.6 Feedback msg |
As no state, feedback is not used |
TRUE |
|
5.4.7 Data integrity |
24-bit CRC and secure hash |
TRUE |
|
5.4.8 Redundancy with cross checking |
All safety information is also used as inverted data to seed CRC. CPU1/CPU2 calculates different parts of CRC/HASH |
TRUE |
|
5.4.9 Different data integrity assurance systems |
ID code and a big CRC/chaskey compared to the payload |
TRUE |
Residual Error Rate¶
RER requirements are stated in 61784-3:2021, 5.8.5.
Reference the RER for detailed calculation.
Radio communication is handled in sheet “3. GenBlackChannel”.
Revision History¶
Date |
By |
Version |
Description |
|---|---|---|---|
2025-08-01 |
Jesper Ribbe |
V01 |
Initial version |