8
YORK INTERNATIONAL
FORM 450.20-N20 (702)
GENERAL INFORMATION
Figure 1. Universal LINC485
UNIVERSAL
LINC485
TX
RX
TX
RX
SCREEN
P3
P2
GND
5VDC
GND
P2
P3
USHL
LAN
PORT 2
LAN
PORT 1
STATUS
S1
MODE
1
2
4
8
16
32
64
CS
OFF ON
Universal
LINC485
Plastic
Housing
DIP
Switches
DIN Rail
Mounting
Plastic
Housing
Universal
LINC485
S1 LINC
OFF ROUTER
ON REPEATER
MODE SWITCH IS
FOR 50K REPEATER
ONLY. SEE MANUAL
CS OFF 19K2 LAN
CS ON 50K LAN
5VDC
Terminology
The terminology to be used to describe the functions
of this manual are as follows:
Network – This is the entire system of RS485
communications or LAN. It includes subnet-
works and the base network.
Base Network – Sometimes referred to as the
backbone. This is the part of the network that
the routers (formally known as PathFinders) are
attached to. When messages are transmitted
from one subnetwork to another, this is the part
of the network which connects the subnetworks.
It is always identified as subnetwork 99.
Subnetwork – A network can be divided into
subnetworks. Each subnetwork is a branch off
the base network, separated from the base
network by a router. The DIP switch on the
router defines the number of the subnetwork,
which must be between 1 and 92.
Segment – Each subnetwork can be divided further
into segments. The RS485 standard has a
limitation of 32 nodes or 4000 ft. (1200 m). To
extend this, a provision is made to allow the use
of maximum of two repeaters in each subnet-
work. This allows each subnetwork to have a
maximum of three segments.
NOTE: The RS485 standard refers to a
segment as a network.
Electrical Node – Every RS485 driver is an electri-
cal node (load) on the network. The RS485
standard limits each segment to 32 nodes (and
4000 ft./1200 m).
Logical Node – Any software address on the
network. A repeater represents two electrical
nodes but zero logical nodes because the re-
peater can bon be addressed directly.
Repeater – A repeater divides a subnetwork into
segments. It essentially strengthens the signal to
allow it to continue to the next segment. Each
subnetwork is allowed a maximum of two
repeaters, providing a maximum of 96 nodes
and 12000 ft. (3600 m). However, since each
port of the repeater is a node (plus one for the
router), the maximum number of logical nodes
which can be installed on a subnetwork is 91.
The orientation of the repeater nodes is very
important when operating using 50 kbaud
communication. To reduce traffic on the network
it uses a filtering method. Refer to the Switch
Settings in Section 4 for additional information.
Router – A router divides the network, or LAN, into
subnetworks. The router connects one port to the
base network as a single node. The other port
connects to the subnetwork as a single node.
Using repeaters on the base network, this allows
a maximum of 92 routers on the base network to
allow 92 subnetworks.
Port 1 of the router must be oriented to the base
network for the router to properly recognize the
subnetwork.
