Troubleshooting
12-4
12.4 LED state of the slave unit
The slave unit also has a status display function via LED.
The display status and primary causes are described respectively.
(1) When “LINK” is lit
The slave unit is not receiving transmission signals. (Transmission waveform error)
Under normal conditions, a voltage of approximately 20 V to 22 V is observed when
measurement is made between transmission lines (DP-DN) in the DC mode of a tester.
If the measured voltage is the same as the power voltage, check that there is no incorrect wiring
of the transmission line.
Also check that there is no error in the machine.
(2) When “LINK” is unlit
The slave unit is not receiving transmission signals. (Transmission signal disconnection error)
Check that there is no contact failure such as looseness in the connection parts of the
transmission line (DP-DN).
Check that power is being supplied to the machine.
Check that transmission signals are reaching the terminal of the transmission line (DP-DN).
Under normal conditions, a voltage of approximately 20 V to 22 V is observed in the DC mode of
a tester.
When the transmission line is disconnected, etc., the position can also be identified by a
difference in the “LINK” display of the terminal.
Example)
(3) When “ALM” is lit
A slave unit status error has occurred. Check the status details and remove the cause of the
failure.
(4) When “ALM” is flashing
The signal voltage of the transmission line (DP-DN) is in a low state.
Check if the power supply voltage for the machine is within the allowable voltage range.
Check that the connection unit and load capacity are appropriate for total extension of the
transmission line and allowable supply current.
(5) When “LINK/ALM” alternately flashes
The machine has detected that the ID (address) of relevant unit is either duplicated or
unregistered.
Check if there is a duplicate of the address or if the ID has been set or not, then set again.
(6) When “ALM” is lit, and “LINK, I/O” is flashing in synchronization
The connection cable for a sensor connected to the relevant unit is disconnected.
* In the case of a slave unit with the sensor cable disconnection detection function.
Flashing Unlit Unlit
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