Hitachi 670 Series Application Manual page 75

1MRK505382-UEN Rev. K
IEC07000239 V2 EN-US
Figure 66:
1. Earth selection connector for IO, screw terminals, 2-pole
2. Earth pin
3. Soft earth pin, see figure
4. X.21 Micro D-sub 15 pole male connector according to the V11 (X:27) balanced version
100k
IEC07000242 V2 EN-US
Figure 67:
Earthing
Three different kinds of earthing principles can be set (used for fault tracing):
1. Direct earth - The normal earthing is direct earth, connect terminal 2 directly to the chassis.
2. No earth - Leave the connector without any connection.
3. Soft earth - Connect soft earth pin (3), see figure
X.21 connector
Communication set-up, 670/650 series
Application Guide
1
1
3 2
The X.21 LDCM module external connectors
67
I/O

100nF
Soft ground
IEC07000242-2-en.vsdx
Schematic view of soft earth
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8
9 15
IEC07000239-2-en.vsdx
66
Section 5
Communication set-up
69