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Appendix D
Command Modem Commands
Answer A The Answer Mode forces the command modem into answer mode. Entering ATA when in the
Command mode will immediately bring the command modem off-hook, out of the command mode and into the On-Line
Answer mode, and cause it to retransmit its carrier signal over the phone line. If no responding carrier tone is received
within thirty seconds (or some other time as determined by S-Register S7), the command modem will cease transmitting
its tone, hang up, and go back into Command mode.
Repeat The Repeat Last Command command causes the command
Last modem to repeat the last command that was executed. The last
Command command will remain stored in the modems command buffer until the Attention command (AT) is
entered. Therefore AT must
A/ not be entered before an A/ command because the A/ will have no effect if an AT command
already cleared the previous command outof the command buffer.
Bell orTone B The B command is used to select the frequency that the CCITT Answer command modem
uses for its answer tone. The answer tone is the tone transmitted by a command modem receiving
a call; this initiates the handshaking between the two command modems.At 2400 bps there is no conflict, because all
command modems use CCITT frequencies. At the lower speeds (0-1200 bps), in the U.S., some modems use the Bell
frequency of 2225 Hz. However, the CCITT specification for V.22 has an answer tone frequency of 2100 Hz. The ATB0
command enables CCITT V.22 (2100 Hz) frequency. The ATB1 command enables Bell 212A (2225 Hz) frequency.
ATB1 is the factory default.
Dial D The letter D in a command will cause the command modem to dial the telephone number
immediately following it. For example, if you enter ATD5551212 and hit Return, the command modem will dial the
number 555-1212. Valid dial characters are 0 through 9, A through D, # , and *. Dial modifiers are: , P R S=x T W ; @
and !. In pulse dialing, non- digit characters have no meaning. The Dial command can also be used in conjunction with a
telephone set for manual dialing. You would dial the number on your telephone set, and after hearing the high-pitched
answer tone on your handset, you would enter ATD on your keyboard and hit Return. You would then hang up the
handset. Unless you have a specific need to dial in this manner, we recommend you use the first method, where the
telephone number is entered on your keyboard.
Echo If the command modem is connected to a full duplex terminal or
Command computer, it will be necessary for the modem to be configured
Mode to echo back characters entered while in the command mode in
Characters order for them to be displayed. The E command is used to
configure the Command mode echo, with ATE0 disabling the
E0-1 echo and ATE1 enabling the echo.
If neither method is selected, the factory default will cause the
modem to echo the command characters.
Load The Load Command Modem Factory Default &F Command
Command resets the S-Registers and command modem commands to the Modemfactory default values.
They are as follows:
Factory Defaults
S-Registers: S0=0, S1=0, S2=43, S3=13, S4=10, S5=8, S6=2, &F S7=30,
S8=2, S9=6, S10=14, S11=95, S12=50, S18=0, S25=5, S26=1, and S28=0.
Commands:
Command Name Default
B1 Answer Tone: Bell
E1 Echo: Enabled
P Dialing: Pulse
Q0 Result Codes: Enabled
V1 Result Codes: Word
X4 Result Code Set/
Call Progress: Dial Tone & Busy