26
System Configuration
Section 2-2
Restrictions on
Connections
The following restrictions apply to CompoBus/S connections:
System with Distinction between Main and Branch Lines
The following diagram shows a CompoBus/S System configuration in which
the main line must be distinguished from the branch lines under either of the
following conditions.
• The system operates in High-speed Communications Mode.
• The system operates in Long-distance Communications Mode with 2-con-
ductor VCTF cable.
• The main line is the cable that connects the ends of the system. The max-
imum length of the main line depends on the communications mode, the
type of cable, and the number of Slaves being used. Refer to
for details.
• A branch line is any cable that branches off the main line. The maximum
length of a single branch line and the maximum total length of all branch
lines in a CompoBus/S system vary according to the communications
mode, the types of cables used, and the number of Slaves. Refer to
for details.
• The Master must be connected at one end of the main cable and the ter-
minator must be connected at the other end. The Master cannot be con-
nected at a point along the main line or on a branch line.
• Only one Master can be connected in the CompoBus/S System. The
range of usable node numbers that can be connected depends on the
model of Master being used and its settings. Refer to
for details.
• Only one Slave can be connected to each branch line. It is not possible to
branch again from a branch line.
• There are three types of cable that can be used (2-conductor VCTF cable,
4-conductor VCTF, and Special Flat Cable), but it is not possible to use
more than one type of cable in the same CompoBus/S System.
System with No Distinction between Main and Branch Lines
The following diagram shows a CompoBus/S System configuration in which
no distinction is required between the main line and the branch lines under
either of the following conditions.
• The system operates in Long-distance Communications Mode with 4-con-
ductor VCTF cable
• The system operates in Long-distance Communications Mode with Spe-
cial Flat Cable
Communications Cable
Master
Communica-
tions Power
Supply
Slave Slave
Slave Slave Slave
Slave
Terminator
Main line
Branch line
Power supply cable
T: T-branch connection
M: Multidrop connection
(Communications power is supplied to each Slave
separately when 2-conductor VCTF cable is used.)