Technical data
Managing Peripheral Devices
8.7 Managing Modems
Table 8–7 (Cont.) DECconnect Accessories
Order Number Description
H8571-C 25-pin male EIA-232 to DEC-423 DECconnect adapter.
H8571-E DEC-423 DECconnect 25-pin adapter with jack screws.
H8571-J 9-pin MMJ adapter. Used with the PC-compatible EIA-574 DB9 wiring.
H8572-00 MMJ cable extender. Allows the direct connection of two BC16E cables.
H8575-A Female 25-pin DEC-423 DECconnect MMJ to EIA-232 general-purpose
adapter.
H8575-B Female 9-pin DEC-423 DECconnect to printer adapter. Also used with
the DB9 wiring found on some MicroVAX console ports.
H8584-AB 8-pin DIN to DEC-423 DECconnect adapter. Most commonly used with
various Apple computers.
2. Choose a type of modem control.
As part of connecting a modem to a device, you can add wires to the host
port and the modem. These wires are used to pass signals called the modem
control signals.
When you connect to a local terminal for dial out, modem control is not
particularly significant: either the modem is wired or configured to ignore
modem control, or the wiring is set up to pass the modem control signals from
the terminal to the modem.
When you connect a modem to a computer, modem control is far more
significant, because the host uses the modem control signals to direct the
modem to accept incoming telephone calls. The modem control signals also
enable the modem to signal the host that a call has been received or that
a call has ended. These signals allow the host and the modem to take the
appropriate actions for a particular event.
Note
In addition to their use by modems, modem control signals are also often
used to communicate device status between the host and other serial
devices such as serial printers. Various serial printers use modem control
signals as modems do: to indicate to the host that the printer is powered
up and ready to accept output, or that the printer is powered down or
otherwise unable to process output.
Table 8–8 contains descriptions of types of modem control that devices can
support.
8–30 Managing Peripheral Devices