Fire-Lite LDM-32F, Instruction Manual

Page: 20 / 64

2. Installation Wiring the EIA-485 Terminal Block
20
LDM-32F PN 50055:C 03/20/01
Supervision Input
The Supervision Input, which requires a normally-closed condition, can be
used for supervising power sources or other devices. It must be power-limited.
If employed, a change in status will be transmitted to the host control panel in
the event of device failure or restoral.
If not used, a jumper must be installed across these terminals on TB1. A trouble
signal will be registered by the control panel if a short circuit does not exist
across terminals 6 & 7.
Figure 9 Wiring Supervision Terminals
Wiring the EIA-485 Terminal Block
A maximum of 32 LDM-32Fs may be connected to the EIA-485 bus, but if
other types of devices are also connected to this bus, the maximum number
of LDM-32Fs must be reduced by the total of such devices. Total annunciation
and switch capability depends upon the number of expander modules used.
Communications between the Fire Alarm Control Panel and the LDM-32F is
accomplished over a two-wire EIA-485 serial communications bus which must
be power-limited. Communications between the host FACP and LDMs is
supervised by the fire alarm control panel.
Wiring Specifications
• The EIA-485 circuit cannot be T-tapped; it must be wired in a
continuous fashion from the control panel to the LDMs.
• The maximum wiring distance between the panel and LDMs is 6000
feet.
• The wiring must be a 18 AWG to 14 AWG twisted shielded pair cable
having a characteristic impedance of 120 ohms, +/- 20%.
• Limit the total wire resistance to 100 ohms.
• Do not run cable adjacent to, or in the same conduit as, 120 volts AC
service, noisy electrical circuits that are powering mechanical bells or
horns, audio circuits above 25 V
RMS
, motor control circuits, or SCR
power circuits.
Note: Never use the shield for grounding purposes. Terminate the EIA-485 shield at the
Fire Alarm Control Panel only.
TB 1 TB 1
Normally Closed
Trouble Contacts
Supervision
Inputs
(5 VDC @
0.5 mA)
Device to be
Supervised
L
D
M32F
-sup
er.cdr
Jumper