IBM 3745 Series, Hardware Maintenance Reference

Page: 234 / 712

Configuration Options
The following table shows the different ways of setting the CNM functions.
CNM Functions
Settable by
NetView PKD MOSS
Manual Command No Yes No
Local wrap (loop 3) No Yes Yes
Local self-test Yes Yes Yes
LPDA-2 No No No
Data Format
Synchronous, binary serial.
Modulation Technique
Bipolar, return-to-zero.
DSU/CSU to Line Interface
The LIC type 6 interfaces the DDS/LDM through balanced impedances matching
the networks (both input and output circuitries may be regarded as 2-port net-
works).
Unbalanced ┌────────────┐
source 5───────┤ Transmit ├──o %──┐
│ terminator │ │ 135 Ω balanced output
┌──┤ stage ├──o %──┘
│ └────────────┘
──┴──
/////
Unbalanced ┌────────────┐
receiver %───────┤ Receive ├──o %──┐
│ terminator │ │ 135 Ω balanced input
┌──┤ stage ├──o %──┘
│ └────────────┘
──┴──
/////
The circuits are not damaged under the following conditions:
Ÿ Open circuit
Ÿ Short circuit between the leads
Ÿ Short circuit from either lead to ground.
The DC isolation between input and output leads with regard to ground is greater
than 20 M
Ω
.
Surge Protection
Primary protection
A line surge protection (carbon block or gas tube) should also be pro-
vided by the line connector before the DCE wall plug.
Secondary protection
One protection device connected from tip to ring and two capacitors,
from tip to frame ground, and from ring to frame ground.
4-82
IBM 3745 Models 130, 150, 160, 170, and 17A: Hardware Maintenance Reference