Black Box MD1640A, MD1641A manual Automatic Leased Line Restoral Operation 336+ Only

CHAPTER 4: Manual Dial and Automatic Answer

4.3Automatic Leased Line Restoral Operation (336+ Only)

When the Series II Modem 336+ (MD1640A) is in Dial Backup mode, it periodically checks the leased line to see if it's operational and tries to restore the leased line if possible. S-Register S18 determines how often restoral attempts occur. The default for S18 is 30 minutes, and can be set in one minute increments from 10 to 255 minutes. Setting the restoral attempts under 10 minutes causes excessive breaks in the dial-up operation.

Note: Both local and remote modems must have S-Register S18 set identically. Refer to Chapter 6 for more information on S-Register S18.

4.4 Manual Dial Backup Call Termination (336+ Only)

With your Series II Modem 336+ (MD1640A) in leased line mode (DIP- Switch #10 in the DOWN position) and with dial backup operation in process, there are two ways to manually terminate the dial backup call (other than automatic leased line restoral). In each case, you will try to establish the leased line connection because it is back in operating condition. The methods of dial backup call termination are:

1)Manual Control. The "Voice/Data" switch can be used to change from a dial back line to leased line by toggling down once. When that is done, the Modem tries the leased line connection, and, if it is good, the modem disconnects the dial back call and establishes a leased line connection.

2)DTR Control. If DTR (Data Terminal Ready) is turned off for 50 milliseconds or more, a disconnect occurs. This is probably the most common method used by computer systems at the automatic answer end of the line to cause the answering modem to disconnect after toggling off procedures.

4.5Dial Backup and Leased Line Restoral (336+ Only)

The dialing associated with the Series II Modem 336+ (MD1640A) when it's in "leased line with dial-back" mode, involves placing a call from the originating modem due to a leased line failure.

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