YORK INTERNATIONAL
25
FORM 450.20-N20 (702)
3
INSTALLATION
switch CS to OFF to operate at 19.2 kbaud and ON to
operate at 50 kbaud.
NOTE: If connecting to an existing
network using Rev. 76 software or
earlier, LAN transfer rates are limited to
19.2 kbaud. For new installations,
Rev. 77, and UCS software, the transfer
rate should be set to 50 kbaud.
The CS switch position is only examined when the
device is first powered up. Any changes made to the
CS switch are ignored unless power is removed and
re-applied.
Continuity and Isolation Checks
CAUTION: Always check for isola-
tion and continuity before applying
power to a network.
A common cause of failure of network devices is
incorrect wiring. Incorrect wiring typically causes
short circuits along the network wiring resulting in
defective RS485 transceivers. Other possible symp-
toms of faulty wiring are open circuits and the
presence of voltage collected by the shielding.
To ensure proper wiring there are several checks that
should be completed before applying power to any
devices on the network. With the LAN connectors
removed from any devices:
1. Check for open circuits on the P2 and P3
conductors. Resistance should be low between
the ends of each conductor. If not, check for
breaks in the wire.
2. Check for short circuits by observing resistance
between the P2 and P3 conductors, P2 and
ground/earth, and P3 and ground/earth. The
presence of a resistance other than infinity
indicates a break in the wire.
