772 B
772 B
The idea is to use:
- X26 : Q2 is doing changeover EMD
- X27 : Q3 is doing changeover EMD
On Q1 DB1.X26 == DB1.DBX301.2 On Q1 DB1.X27 == DB1.DBX301.3 On Q1 DB1.X28 == DB1.DB301.4
So in this case using priority:
- Q1 can always change format because the AIR is taken from ALPLA
- Q2 can always start the change and will not pause.
- When Q2 is changing is set the X26 bit
- Q3 must wait until X26 signal is off to start the changeover
- If Q3 is doing the changeover and the X26 bit is set, then must pause until X26 is clear
- When Q3 is changing is set the X27 bit
- Q4 must wait until X26 and X27 signal is off to start the changeover
- If Q4 is doing the changeover and the X26 or X27 bit is set, then must pause until X26 and X27 are cleared.