Timing - GE Multilin MM3 Motor Manager 3 Instruction Manual

MM3 MOTOR MANAGER 3 MODBUS PROTOCOL
8.1.6

Timing

8–4
The algorithm is:
1. FFFF hex —> A
2. 0 —> i
3. 0 —> j
4. Di (+) AL —> AL
5. j + 1 —> j
6. shr(A)
7. is there a carry? If No, go to 8; If Yes, G (+) A —> A
8. is j = 8? If No, go to 5; If Yes, go to 9.
9. i + 1 —> i
10. is i = N? If No, go to 3; If Yes, go to 11.
11. A —> CRC
Data packet synchronization is maintained by timing constraints. The receiving device
must measure the time between the reception of characters. If 3.5 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.
CHAPTER 8: COMMUNICATIONS
MM3 MOTOR MANAGER 3 – INSTRUCTION MANUAL