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Chapter 3 – Operation
Multi-Tech Systems, Inc. MT9234ZBA-Series User Guide (S000387A) 13
Chapter 3 – Operation
About the Front Panel
The LED indicators on the front panel indicate status, configuration, and activity:
TD – Transmit Data. Flashes when the modem is transmitting data to another modem.
RD – Receive Data. Flashes when the modem is receiving data.
CD – Carrier Detect. Lights when the modem detects a valid carrier signal from another modem. It is on when the
modem is communicating with the other modem, and off when the link is broken.
56 – 56K Mode (56,000–28,000 bps). Lights whenever the modem is set for or connects using the V.90 or V.92 protocol.
The actual connection speed depends on ISP server capabilities and line conditions.
33 – V.34 Mode (33,600–2,400 bps). Lights whenever the modem connects using the V.34 protocol.
14 – V.32bis Mode (14,400–7,200 bps). Lights when the modem connects using the V.32bis protocol. The modem can
connect at lower than V.32bis speeds, but no speed indicator lights during the connection.
OH – Off-Hook. Lights when the modem is off-hook, which occurs when the modem is dialing, online, or answering a
call. Flashes when the modem pulse-dials.
TR – Terminal Ready. Lights when a communications program is using the modem. It means the modem is ready for an
outgoing or incoming call. It goes off when the communications program disconnects the serial port. When it goes
off, a connected modem will also disconnect.
EC – Error Correction (V.42). Lights continuously when the modem is in V.42 error correction mode, and flashes when
compression is activated.
FX – Fax. Lights when the modem is in fax mode.
Note: When you turn on the modem, the protocol indicators flash briefly as the modem does a self-test, after which the
56 indicator lights. After a call, the indicator for the protocol used in the connection remains lit until another call is
made or the modem is reset. If you connect at a rate under 14,400 bps, all protocol indicators remain off after the
connection is broken, even though the modem is still turned on.
Leased-Line Operation
The MultiModemZBA modem can be used on a two-wire leased line.
A leased line is a private, permanent telephone connection between two points. Unlike normal dialup connections, a
leased line is always active. The modems automatically connect when they are attached to the line and are turned on.
Because a leased line is always active, one of the two modems on the line must be configured as the originate modem
and the other as the answer modem; however, it does not matter which is which.
In the event of an interruption, leased-line modems automatically reconnect when the data line or power is restored.
Setup
1. Open the modem and change jumper J2 to select leased-line operation, and jumper J3 to select either
originate or answer operation, depending upon how you intend to use the modem. See Chapter 2 for the
detailed procedure.
2. Connect a modular telephone cable to the LINE jack. Connect the other end of the cable to a two-wire
lease-line jack or terminals supplied by the telephone company.
3. Turn on the modem.