Multi-Tech Systems BL-Series manual 25bis AT Commands, Enable/Disable V.25bis Mode $V Command, 150

MultiModemBL User Guide

V.25bis AT Commands

The AT commands associated with V.25bis mode are described as follows. Note that one command enables and disables V.25bis mode and the rest are only operable in the V.25bis mode.

Enable/Disable V.25bis Mode ($V) Command

The function of the $V command is to select the V.25bis mode in asynchronous mode. (Synchronous mode is set up with switches. For example, the modem could be in AT command mode, (AT$V1), and if synchronous mode is enabled with AT Command mode enabled, then V.25bis mode is selected). Prior to executing this command, make sure that your modem is properly set up to perform the type of operation you will be performing. Refer to the initialization section of this appendix for information about modem set-up. When in V.25bis mode, most normal AT commands will also function (except D,N,O and U). V.25bis operates in asynchronous or synchronous modes (depending on the position of DIP-Switch #12), and does not check for terminal speed (so do not change speeds while in this mode) or parity. In synchronous mode, speed is not important since the internal clocks provide synchronization.

To place your modem in V.25bis mode from asynchronous mode, enter the AT$V1 command. To return to AT command mode, enter the AT$V0 command. AT$V2 allows you to run one V.25bis command from AT command mode without leaving AT command mode (the V.25bis command follows $V2 on the command line).

Change Serial Baud Rate (CSP) Command

The CSP command will change the serial baud rate of your modem by entering CSPsssss where

ssssscan equal:

0300	=	300 bps
1200	=	1200 bps
2400	=	2400 bps
4800	=	4800 bps
9600	=	9600 bps
19200	=	19200 bps
38400	=	38400 bps
57600	=	57600 bps
115200 =		115200 bps (1932 and 2834 Series only)

Dial Phone Number Provided (CRN) Command

The CRN command permits the dialing of the phone number immediately following it (from the command line). It is similar to the D command of the AT command set, except that the number is first checked against the Delayed Number and Forbidden Number list. If permitted, depending on the country regulations in effect, the number will then be dialed. For example, if you enter CRN7859875 and hit RETURN, your modem will check the two lists. If the number is on the Delayed Numbers list, you can dial that number again after t minutes have passed. If the number is on the Forbidden list, a CFIFC message will be displayed.

You can use various commands from the AT command set within the CRN command line to facilitate the dialing process, such as P, T, or : for pulse dialing, tone dialing and wait for dial tone. V.25bis supports “smart” dialing.

To dial a phone number, enter CRNdd...dd where dd...dd is the phone number, which can be up to 20 characters long using any character on the telephone pad (0 through 9, *, #, P, T, and :).

Some additional dialing characters may be available, based on country regulations.

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