Liebert RCM8DO - Manual (Page 17)

Section 2: Installation
Proprietary EIA-485
The EIA-485 port is a proprietary connection that allows
you to network multiple RCM8 units in a "daisy-chain"
configuration. Multiple unit configurations must include a
"master" unit to which three or four "slave" units can be
connected; repeaters may also be daisy-chained.
Liebert recommends a
maximum cable length of 3280
feet. Use a twisted-pair wire
and maintain polarity (+/
− ). The
slave unit at the end of the
string (the last RCM8) must
have the P4 jumper set to IN.
The P4 jumper on all other
units must be set to OUT.
Use 18-22 AWG stranded, twisted-pair wires. Run the EIA-
485 cable from the EIA-485 terminal block to other EIA-485
terminal blocks in the same string. Set the P4 jumper on the
last slave unit IN: set the P4 jumper on all other units OUT.
Maintain +/
− polarity.
Proprietary EIA-422
The EIA-422 is a proprietary connection to a Liebert
SiteScan system. The SiteScan system data file must include
the RCM8 as a contact closure module. Alarm text for
RCM8 units connected to SiteScan is entered through the
RCM8 using a PC or terminal. In multiple RCM8
configurations, each slave unit transmits only its own
alarms; the master unit transmits all alarms.
Run the EIA-422 cable from the EIA-422 terminal block on
the master unit to the appropriate terminal block number of
the SiteScan system.
Liebert recommends a
maximum cable length of 3280
feet. Maintain polarity (+/
− ).
3. Apply power to the system and configure the unit
parameters as described in Section 3 of this manual.
Modem
The modem port is a standard EIA-232 (DTE 25-pin male,
1200 or 2400 baud) connection for a dial-up modem, null
modem cable, short haul modem, or leased line. Alarms that
are configured to transmit use this port.
Liebert recommends a
maximum cable length of 50
feet for any device connected
to the modem EIA-232 port.
First, connect the modem, power, and phone cables as
directed in the documentation that came with your modem.
Next, using a standard 25-conductor EIA-232 cable, connect
one end to the 25-pin Modem port on the RCM8. Connect
the other end to the 25-pin EIA-232 port on the modem. Be
sure all connections are secure to ensure proper operation.
Communications parameters for this port are fixed 7 data
bits, even parity, and 1 stop bit. Refer to the dial-up
modem setup information later in this Section for other
settings related to the modem.
Liebert RCM8 • 11