VooDoo DCR 6000, Planning & Installation Manual

Page: 127 / 149

6. Interfaces DCR 6024/6128/6000
6 – 8 Planning and Installation – Rev. 1 / 7. 2001
A and B are defined as shown below:
Fig. 604:
When the DCR 6024 receives a command telegram from the control system, it
sends back the following return telegram:
If the DCR 6024 receives a command without data request:
... AK (10H, 01H) = acknowledgement of receipt.
If the DCR 6024 receives a command with data request:
... answer code + data
If transmission error is detected or if an undefined command is received:
... NAK (11H, 12H) + error code
Error code: Bit0 (01H): Command not defined
Bit2 (04H): Checksum error
Bit4 (10H): Parity error
Bit5 (20H): Overrun error
Bit6 (40H): Start/stop bit error (framing error)
Bit7 (80H): Time out
The control system must not send any additional command telegram before having
received a corresponding response to the previous command.
The control system must not interrupt the transmission of a command telegram for
more than 10 ms. As soon as the DCR 6024 has detected such a break which is
longer than 10 ms it proceeds with a time out error sequence. The DCR 6024
ignores the command telegram received and transmits a NAK (time out).
As soon as the DCR 6024 receives a command telegram from the control system,
it sends a return message within 9 ms. Therefore, unless having received a return
message from the DCR 6024 within 10 ms after the execution of a command tele-
gram transmission, the control system must proceed as if the communication had
not taken place under normal circumstances.
When an error is detected, the DCR 6024 immediately sends a NAK to the control
system. Upon receipt of a NAK, the control system in turn must immediately abort
the data block transmission.
Communication
protocol