BCU Does Not Communicate with UCMs
BMTW-SVN01F-EN 209
Problems with the Modem and Phone Line
The following presents guidance in proper modem configuration and
phone line connection:
• The BCU uses an ISA bus-style modem. BAS recommends that you
use only modems supplied by Trane for use in the BCU. The modem
must be hardware configured for Comm1 and IRQ4.
• You cannot use an EIA-232 card and modem card at the same time in
a BCU, even though you may have an open card slot available in
which to insert them.
• The modem phone line must be connected to the line connection port
on the modem rather than the telephone connection port.
• Connect a phone to the line, check for a dial tone, and verify that the
phone can make and receive calls.
• An in-line transient protection device may be needed on the phone
line to prevent transient electrical signals from affecting the modem.
Problems with the BCU Modem Programming Setup
Follow these guidelines for proper modem programming setup:
• The modem will not work at all until the BCU has been programmed
to have a modem object. Verify that the BCU has a modem object.
• If the phone line goes through a local phone system within the build-
ing, additional wait times and access numbers may need to be pro-
grammed into the phone numbers being used for dial out and remote
access.
• Verify that the correct phone number is being used when attempting
to dial into a BCU.
BCU Does Not Communicate with
UCMs
UCM communication problems can generally be divided into two main
groups:
• Communication failures on initial installation
• Communication failures that occur after initial installation
Communication Failures on Initial Installation
Failures that occur during the initial installation can generally be traced
to:
• Wiring errors, i.e., wrong polarity, shorts between conductors, open
wires, bad high-resistance connections, use of wire with too high
capacitance, too long total communication-link length (high resis-
tance), wrong connections at the BCU or UCM, etc.
• Communication failures caused by nearby strong sources of
EMI/RFI interference
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