Troubleshooting
11-4
11.4 LED state of the slave unit
The slave unit also has a status display function using LEDs.
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 17V to 18V is observed when measuring between
transmission lines (DP-DN) using a tester in DC mode.
If the measured voltage is the same as the power supply voltage, check that there is no miswiring of the
transmission line.
Also check that there are no master unit errors.
(2) When "LINK" is not lit
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 master unit.
Check that transmission signals are reaching the terminal of the transmission line (DP-DN).
Under normal conditions, a voltage of approximately 17V to 18V is observed using a tester in DC mode.
When the transmission line is disconnected or suffers a similar fault, 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 fault.
(4) When "ALM" is flashing
The signal voltage of the transmission line (DP-DN) is in a low state.
Check that the supply voltage of the gateway is within the allowable voltage range.
Check that the connection unit and load capacity are appropriate for the total length of the transmission
line and allowable supply current.
(5) When "LINK/ALM" alternately flashes
The gateway has detected that there is a redundant ID (address) of the applicable unit or the ID is not
set.
Check if there is a redundant address or if the ID has been set, and then set again.
(6) When "ALM" is lit, and "LINK, I/O" is flashing in synchronization
The connection cable of the two-wire type sensor connected to this unit is disconnected.
* Disconnection can be detected for two-wire type sensors only.
Flashing
Unlit Unlit
X
Fault location
