GE 90-30 PLC Series Installation And Hardware Manual page 266

Remote baseplates IC693CHS393F (and later) and IC693CHS399E (and later) have a change
inside the baseplate which eliminates the need to remove pin 1 from the mating cable. When using
factory made Wye cable with these baseplates, it is not necessary to remove pin 1 from the cable.
Custom built Wye cables for these baseplates can be made using either Figure 10-20 or Figure 10-
21. Figure 10-21 shows how the standard (factory made) Wye cables are made.
By removing pin 1 in custom built Wye cables made for the earlier versions of remote baseplates,
the pin 7 (0V) signal reference originates in the main (CPU) baseplate. In these earlier versions of
the remote baseplates, pin 1 was tied to pin 7 (0V) and also AC coupled to the remote frame
ground. When using these baseplates in combination with the 100% shielded Wye cables, the pin 7
(0V) reference would be improperly DC coupled to the remote frame ground through the D-
subminiature connector shell, which is DC coupled to the remote frame ground.
In the remote baseplates IC693CHS393F (and later) and IC693CHS399E (and later), the pin 1
shield signal is DC coupled to the remote frame ground and not attached to pin 7 (0V). This allows
the best noise immunity by providing a good continuous cable shield, and still allows the pin 7
(0V) signal reference to originate in the CPU baseplate without the need for removing pin 1 in any
factory or custom built cable. The D-subminiature connector shell is still DC coupled to the remote
frame ground.
Making a 100% Shielded Cable
Use the following steps to build a 100% shielded cable:
1.
2.
3.
4.
5.
6.
7.
GFK-0356Q Chapter 10 Cables
Strip approximately 5/8 inch of insulation from your custom cable to expose the shield.
Remove the male Pin 1 from any connector plugging directly into an older version remote
baseplate (IC693CHS393E, IC693CHS399D, or earlier).
Put split-ring ferrule over cable insulation (Figure 10-17).
Fold the shield back over top of the cable insulation and ferrule.
Place the collar of the metal hood over top of the folded shield and securely clamp the hood.
Test your cable for continuity between both connector shells. Connect an ohmmeter between
the shells and flex the cable at both ends. If the metallized connector hood is not making
proper contact with the cable shield at either end, the connection will show intermittent
continuity on the ohmmeter.
Plug the metal hooded cable onto a remote baseplate expansion port connector or into a GE
WYE cable and securely tighten the two screws. Installing and tightening the screws
will electrically connect the shield to the remote baseplate frame ground, which should in turn
should be connected to earth ground as instructed in the "Installation" chapter, under the
heading "Baseplate Safety Grounding."
10
Cables
10-27