Mitsubishi Electric Melsec-k Instruction Manual page 70

I
5. OPERATING PROCEDURE
(3) Sometimes communication error occurs, resulting in disconnected channel
Master channel
In the case of K3CPUP2: CRC error display
"LE
4
''
Number 1 slave channel
/
/
/
/
/
/
I
Number 5 slave channel
I
CRC: Off
9
Number
2
slave channel
CRC: Off
Number 3 slave channel
Number 4 slave channel
CRC: Lit instantaneously
CRC: Lit instantaneously
Note: Make check in order of optical fiber cable connection.
(In this case, there is no relation to channel number.)
Fig. 5.3
As shown in Fig. 5.3, carefully looking a t the LED display "CRC" of each channel in the loop
allows judgement where the error exists in the loop. Carefully look a t the LED "CRC" in due
order, beginning with that of the master channel. When the LED of channel is always off,
channels upstream of that channel are normal. i f there is a channel of which LED has been lit
instantaneously, the error is due to one of the following factors. (Between Number
2
and 3
channels in Fig. 5.3)
1) The optical fiber cable is connected improperly. (Between Number 2 and 3 channels in Fig.
5.3)
2)
Failure of optical transmitter located upstream by
1
channel (Number
2
channel in Fig. 5.3)
3) Failure of optical receiver of i t s own channel (Number 3 channel in Fig. 5.3)
4) Hardware error of link channel (Number 2 or 3 channel in
Fig. 5.3)
(4) Sometimes communication error occurs, resulting in disconnected channel
Carefully looking a t the LED display "RC" may indicate the failure of optical receiver. Normal-
ly, the LED "RC" is lit lightly. However, if the optical receiver has error, the LED may become
dim instantaneously. In this case,
it
can be judged that the receiver of that channel is defective.