
B-62714EN/04 MAINTENANCE 1.16/18/21-B, 16/18-C
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1.2 LED INDICATIONS AND THEIR MEANINGS
On the I/O Link-II board used with Series 16/18-B/C and 21-B, four
green LEDs (STATUS), three red LEDs (ALARM), and four green
LEDs (LEDM1) for software control display are provided for status
indication at the top of the front of the panel.
In the description below, each LED has one of the following states:
A : Turned off B : Turned on C : Blinking D : Irrelevant
I/O
LINK-II
1 2 3 4
STATUS
LARM
LEDM1 9 8
11
10
STATUS LEDs (green)
No. LED indication 1 2 3 4 Board state
1 STATUS B A A A
The I/O Link-II board is operating
normally.
2 STATUS B C A A
DI/DO data transfer is being performed
normally.
ALARM LEDs (red)
No. LED indication 1 2 3 Board state
1 ALARM B A A A RAM parity error occurred.
LEDM1 (green)
No. LED indication 1 2 Board state
1
B B
B B
State immediately after power-on
2
A A
B B
The communication board is being
initialized.
3
A A
C A
The communication board software is
running.
4
A B
A A
A RAM parity error occurred.
5
B B
A A
An F-bus error occurred.
6
B A
A A
An F-bus system emergency occurred.
7
B A
C D
A communication error (such as an FCS
error, command error, frame length error,
and response timeout) occurred. This
indication is provided if a communication
error occurs even once.