Controls on PC Board. Black Box MD1641A, MD1640A

SERIES II INTELLIGENT DATA/FAX MODEMS

13) FAX (FX).

This LED is lit when the modem is connected in FAX mode.

14) 336+ (MD1640A) only: ERROR (ERR).

When this LED is lit, either the leased line is down and the modem is in dial backup mode, or else the self-test has failed.

1.9 Controls on PC Board

The Series II Modem is designed on a single printed circuit (PC) board.

This board contains one 16-position DIP-Switch (numbered 1-16). The

DIP-Switches are accessible through a cut-out on the side of the modem. There is also a knob which is used to adjust the speaker volume. This knob is accessible through the modem's rear panel.

The sixteen DIP-Switches control various modem options or set default values for Command Mode operation. There is a difference in how several of the switches operate depending on whether you are in synchronous or asynchronous mode. Refer to the switch label on the bottom of the Modem for an exact list of the switch functions in asynchronous and synchronous operation.

Chapter 9 of this manual also provides detailed instructions on configuring all of the Modem's PC board options.