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CHAPTER 4: Installation
4.2 Connecting a Modem to the PM Switch
The PM Switch can be controlled either by a local PC that communicates with
the unit across a single cable, or by a remote PC that communicates across a
modem link.
The PM Switch’s “Modem Mode” provides several useful options that can be
employed when the unit is controlled by modem. The Modem Mode, which is
only available on PM Switch Ports 1 and 2, provides password-protected access
to the Command Mode, and allows the user to redefine the Modem Reset
Message and Hang-Up Message.
NOTE
An external modem can also be connected to any other PM Switch port,
providing that the modem does not require password protection, an
externally generated reset message, or a hang-up message.
The Modem Mode can also provide password-protected access to the
Command Mode when the PM Switch is controlled by a local device that
communicates with the unit across a single cable.
Regardless of whether the unit will be controlled locally or remotely, the
Control Device should communicate with the PM Switch through Port 1. This
allows access to the unit if the PM Switch is initialized to default parameters.
In the default state, Port 1 is the only port with access to all
PM Switch commands. (After the PM Switch has been installed and
configured, Port 2 can also be connected to a modem to allow remote access
to the Command Mode.)
To connect a modem to the PM Switch, first attach an appropriate modular
adapter to the modem’s serial port. You can use the modem-style adapter
included with the PM Switch for this purpose if you want to. This adapter has
a DB25 male connector and is pinned to interface with standard
asynchronous modems. See
Appendix A for a description of the adapter
pinouts, end-to-end pinning, and the product codes of the relevant adapter
kits if you want to build your own adapters. If you want to order assembled
adapters instead of building more, call Black Box for a quote.
After you attach the adapter, run a six-wire, straight-through-pinned twisted-
pair or flat-satin cable with RJ-11 connectors—either one of the cables
included with the PM Switch, or a cable just like them—from the adapter to
PM Switch Port 1. Our product codes for these cables are EYN725MS for
twisted-pair or EL06MS for flat-satin.