Honeywell LC13-510, Manual, Page: 12 / 76

Dual Node Module Service 2-2 9/95
2.2
2.2 BASIC MODULE CONFIGURATIONS
A Dual Node Module can accommodate one or two nodes. In a Dual Node Module, there
is only one connection to the LCN A coaxial cable and only one connection to the LCN B
cable. These connections are made at the CLCNA and the CLCNB boards, respectively,
using BNC T-connectors. The LCN signals are communicated between nodes within a
Dual Node Module by RS-485 signals on the backpanel. RS-485 is an electrical signaling
standard. The CLCNA and CLCNB boards provide interface conversion between the RS-
485 backpanel signals and the LCN network.
Table 2-1 shows the basic (minimum) module configurations for single- and double-node
modules. The Application Module (AM) uses the basic configuration. Other module types
require additional boards, as covered in subsection 2.3. Figure 2-2 is a rear view of a Dual
Node Module showing the LCN A and LCN B coaxial cable interconnects and the RS-485
terminator assemblies that are installed on the backplane at the top and bottom ends of the
RS-485 signal conductors. Four terminator assemblies are required—two at the top and
two at the bottom of the backplane.
CAUTION
SlCLCNA and CLCNB boards. Do not plug any other type of board into these slots unless
specifically authorized by Honeywell documentation, or damage may result. This is particularly
true for CSR boards—DO NOT plug a CSR board in I/O Slot 1.
As shown in Table 2-1, the CLCNA and CLCNB boards are installed in different nodes in
a Dual Node Module. The CLCNA is installed in the upper node, and the CLCNB is
installed in the lower node. Each is installed in Slot 1 (the lowest slot) in the I/O card cage
of its respective node. The CLCNA and CLCNB boards each receive power from both
power supplies in the Dual Node Module. Therefore, if one power supply is not present,
or is turned off to perform troubleshooting or maintenance on one node, both the CLCNA
and CLCNB boards will receive power and the node which does have power will continue
to have access to both the LCN A and LCN B cables in the LCN network. The CLCNA
and CLCNB are the only boards in the I/O card cage which are powered from both power
supplies. The Fan Assembly is also powered from both power supplies. It will operate if
either supply is on (or if both are on). The CLCNA and CLCNB boards are designed to be
able to be plugged into and unplugged from the system while power is on, allowing them
to be changed without removing power from a node. Do not attempt to do this with any
other board type.