Omron G9SP Series Manual page 42

- Checksum Calculation Subroutine
Step
(1) Control Freeport communication for port1 This processing is performed once at startup.
(2) Enables the 150ms-timer event, receive complete event and send complete even. This processing is performed
once at startup.
(3) Once 100 ms has elapsed,to process each 300ms the counter is added
(4) Once 300 ms has elapsed, enables receive complete event.
(5) Once 300 ms has elapsed, the fixed portion of the send command is set.
(6) G9SP communications reception data is set to the send command from I 0.
(7) The checksum calculation subroutine given above is called, and the checksum of the send command is calculated.
(8) The checksum and the end code are set to the transmission command.The send command is transferred to the
RS-232C send port, which enables sending to the G9SP-series Controller.
(9) The timer is restarted and the next send processing is performed after 300 ms.
(10) The checksum calculation subroutine given above is called, and the checksum of the reception response is
calculated.
(11) The checksum of the reception response and the end code are checked, and the G9SP Communications
Transmission Data is copied to Q 0 and Q 3 and G9SP Safety Input Terminal Data is copied to Q 4 to Q 9.
(12) After the transmission is completed, the reception interruption is enabled.
3-10
Description