Figure 4-1 presents the cables required for install-
ing the IBM 2702/03 Transmission Control Units.
Since the selection of the transmission adapters incor-
porated into a particular 2702/03 unit installation
depends on customer requirements, the figure does
not indicate the specific cable groups nor the quantity
of each for a given system. The selection of
machine features affects the choice and quantity of
cable groups. The identification and the purposes
of the cables available are listed in Tables 4-1 and
4.2. The cables to attach the specific 2702/03
features ordered are supplied by IBM with the
2702/03 Transmission Control Unit.
The cable plugs (inserted in IBM equipment) are
identified as Style A, PN 5353867 (light gray),
Style B, PN 5353868 (dark gray), and Style B,
PN 5353869 (dark gray without threaded insert.
See Figure 4-2.
The contacts used in the IBM cable plugs are called
serpent contacts. The serpent contact is a herma-
phroditic, gold-plated phosphor bronze, dual-mating
(See Figure 4-3.)
Termination is accomplished by the bare-wire crimp
method. Three contacts are available to cover the
range of solid or stranded wire sizes required:
0.042 to 0.103
0.028 to 0.103
CHAPTER 4. EXTERNAL CABLING
Voltage Ratings. The maximum voltage rating of this
connector is 24 volts ac or dc.
above 24 volts, contact the local IBM representative.
Current Rating. The maximum continuous current
rating of each contact is 3 amperes. The contacts
are not intended for interrupting current_
Resistance. The termination-to-termination resist-
ance (includes 2 crimps and mated contacts) will not
0.020 ohms when installed on #22 AWG and
2. 0.030 ohms when installed on #24-#26 AWG wire.
3. 0.040 ohms when installed on #28-#32 AWG wire.
Insulation Resistance. The contact-to-contact insu-
lation resistance is 100 megohms (minimum) meas-
ured at a test potential of 100 volts dc, after exposure
of 1 hour at a temperature of 38
C and 85-90%
The cables used to connect the 2702/03 to the I/O
channel or to the communications facilities and their
plug positions within the 2702/03 are shown in
Figures 4-4 through 4-17.
Emergency Power Off (EPO) Cabling
An EPO cable must be installed for each CPU con-
nected to the 2702/03.
the Two-Processor Switch
feature is installed, both CPUs must drop power in
order to drop 2702/03 power. Either CPU can bring
2702/03 power up. The EPO cable to the IBM 2711
Line Adapter Unit allows the IBM 2711 's powering
to be controlled by the 2702/03. See Figure 4-4 for