3.2.1.2 Asynchronous Controllers With Modem Support
Serial devices with modem support require two modems: one connected to the
system and one connected to the remote terminal. Both must be connected to
phone lines.
Before using modems with your system:
1. Make sure each modem is connected to the system.
2. Make sure each modem is properly installed and connected to a phone jack.
3. Set the controls on each modem according to instructions in the modem user’s
guide.
Before using the modem connected to the remote terminal:
1. Make sure the modem is properly installed and connected to a phone jack.
2. Set the controls on the modem according to instructions in the modem user’s
guide.
3. Check the settings on the terminal attached to the modem.
Depending on the type of modem and type of lines used, the baud rate can
be 1200, 2400, 4800, or 9600. Other settings should be the same as those
described in the previous section.
Before using a phone line with modem support, you must set certain parameters
such as line speed. See your system software manuals for details.
3.2.2 Synchronous Controllers
The following synchronous controllers are available for your system.
• DIV32—DEC Integrated Services Digital Network (ISDN) controller
• DPV11—Single-line programmable controller
• DSV11—Dual-line controller
Before using a synchronous controller you must verify the following.
• The system you want to communicate with has an appropriate synchronous
controller.
Synchronous communications require a synchronous controller on the
transmitting system and the receiving system.
• The transmitting and receiving systems have supporting software installed.
Synchronous communications operate under protocols that define how data is
interpreted. Two common protocols are X.25 and PSI. Appropriate software is
required to interpret the protocol.
Operating the System Options 3–37
