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Starting sequence
On power--up, the board's CAN controller reads in the bus speed from the
micro processor: 400 kbit/s.
The circuit board displays the starting sequence from power--up.
LED1 lights red. Then LED1, LED2 and LED3 lights green.
When the board has been initiated, and the power source is in the application
program, LED1 flashes continously with a green light.
LEDs on circuit board 20AP1
Communication interruptions
If the CAN bus fails, the control panel will normally generate a fault message.
Check the following points in the event of problems with CAN communications:
The terminating resistor. The CAN bus resistance must lie in the range
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50--130 ohm the optimum value is 60 ohm. To check the resistance, turn
off the power source and measure the resistance between pins L and K in
connector socket XS3 on the front of the machine.
The connection cable between units. Check that the correct type of cable
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is being used. Check that each signal is being carried by the correct core.
CAN H and CAN L must be carried by the twinned pair.
All screen connections must be sound.
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Good contact with the chassis connections from/to the control board,
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suppressor board and suppressor capacitors. See the main circuit
diagram.
Terminating resistors
In order to avoid communication interference, the ends of the CAN bus must
be terminated by resistive loads.
Principal diagram of the CAN bus and connecting up of the terminating resistors
cu19_20_1
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S0740 800 191/E080229/P78
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