Specifications
Cable Construction Information 15
Cable Construction Information
If you plan to construct your own HSI cables, be sure to observe the
guidelines given below.
Wire Gauge, Grounding, and Pairing
• Use 26 or 24 AWG wire. Contacts should be 30 microinch gold
flash.
• The cable must be grounded both by a drain wire connected to
pin 1 on both sides (pin A on the type M connector) and by the
braid. Both the drain wire and the braid must be connected to
the connector case and shell at each end of the cable. The braid
must be connected through its full circumference.
• Unused wires must be connected to the cable shield at one end.
• Use an anti-EMI shield.
• Important. Wires identified by a rectangle under the heading
“Twisted pair” must be installed as a twisted pair. If you do not
install twisted pairs correctly, the cable will not work.
Type of Connectors
The HSI port accepts a 26-pin, 3-row male connector. The types of
connectors used on the interface-specific end of the cable are as
follows:
Table 3. Connector Types
Cable Type Connectors
V.24 modem DB25, HSI
V.35 modem Type M, HSI
X.21 modem DB15, HSI
V.24/V.35 null-modem HSI, HSI
X.21 null-modem HSI, HSI
V.35-AS/400 null-
modem
Type M, HSI
Null-modem conversion HSI, HSI