Timing - GE 469 Communications Manual

MODBUS PROTOCOL

Timing

4
5. j + 1 --> j
6. shr (A)
7. Is there a carry?No: go to step 8.
8. Is j = 8?
9. i + 1 --> i
10.Is i = N?
11.A --> CRC
Data packet synchronization is maintained by timing constraints. The receiving device
must measure the time between the reception of characters. If three and one half
character times elapse without a new character or completion of the packet, then the
communication link must be reset (i.e. all slaves start listening for a new transmission from
the master). Thus at 9600 baud a delay of greater than 3.5 × 1 / 9600 × 10 = 3.65 ms will
cause the communication link to be reset.
Yes: G (+) A --> A and continue.
No: go to 5.
Yes: continue.
No: go to 3.
Yes: continue.
469 MOTOR MANAGEMENT RELAY – COMMUNICATIONS GUIDE
COMMUNICATIONS GUIDE