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6.0 PINOUT GUIDES
6.1 Modem Setup and Pinout Guide
The OpenComms EM must be connected to a modem to send pager alerts when a sensor reading
crosses a user-defined threshold (see 5.5.2 - Modem Setup for more information).
The unit is compatible with modems that have DB9 or DB25 serial COM ports. A proper cable must
be constructed to allow communication between the unit and the modem. This cable connects the
RJ45 connector labeled Modem on the back of the unit to the serial port on the modem.
Refer to Table 13 for a pinout guide for building the correct cable. For more information on construct-
ing this type of cable, call Liebert Monitoring Application Support at 1-800-222-5877 or contact your
local Liebert representative.
6.2 Contact Closure Cable Pinout Guide
All OpenComms EM models can
accommodate a contact closure cable in
either sensor port. Contact closure cables
are available separately from Liebert in
various lengths (see Table 3).
To make your own contact closure cable,
refer to Table 14 for the pinout for this
cable.
• Pin 2 is the contact that may be
defined as either Normally Open or
Normally Closed.
• Pins 6 and 8 must be tied together to
form the common.
6.3 Serial Cable Pinout Guide (EM PDU & vEM-14 Controllers)
The serial cable included with
OpenComms EM PDU and vEM-14 con-
trollers is designed for connecting the
OpenComms EM unit to an MP
Advanced power strip.
To make your own cable, refer to
Table 15 for the pinout for this cable.
Table 13 OpenComms EM to DCE modem pinout guide
RJ45 Pin # Signal Name Description DB25 Pin # DB9 Pin #
1 DTR Data Term Ready 20 4
2 CTS Clear to Send 5 8
3 GND Signal Ground 7 5
4 TXD Transmit Data 2 3
5 RXD Receive Data 3 2
6 CD Carrier Detect 8 1
7 RTS Request to Send 4 7
8 DSR Data Set Ready 6 6
Table 14 Contact closure cable pinout
OpenComms EM RJ45 Dry-Contact Device
1—
2 Normally Open or Normally Closed
3—
4—
5—
6 Common - tied to Pin 8
7—
8 Common - tied to Pin 6
Table 15 Serial cable pinout - MP Advanced Power Strip
OpenComms EM RJ45 MP Advanced power strip
18
23
32
45
54
6 Not Connected
7 Not Connected
81