Mitsubishi MELSEC-A AJ71PT3 User Manual page 54

4. PRE-OPERATION SETIING AND PROCEDURE /MELSEC;4
(2) Corrective action
Check the RD and SD LEDs of all stations in data link cable
connection order, beginning with the master station transmis-
sion (SD) LED. Check the link unit hardware and data link
cables as explained below:
LED off
•
o
Fig. 4.9 RO/SD LED States at Line Error Occurrence
aster station Station 1
Station 2
Station 3 Station 4 Station n
o'ff..
'((0:
:0.
:0:
1\
0
0 0
0 0
RO ISO ROI
[so
Rol
[so
RO
tso
Rol
SO
---~
IS
M
In Fig. 4.9, the RD and SD LEDs on station 3 are off possibly
because:
(a) The data link cable between station 2 SD and station 3 RD
is not connected, is broken or its length is greater than the
maximum interstation transmission distance.
• Check connection of the data link cable.
• Change the data link cable.
• Check the cable connection distance.
(b) Data link unit hardware of station 2 is faulty.
• Connect the cable between station 1 SD and station 3
RD.
(c) Data link unit hardware of station 3 is faulty.
• Connect the cable between station 2 SD and station 4
RD.
•
I
4-13 - - - - - - - - - - - - - - - - - -
18(NA) 66164-A