ISDN Data and Telephony Protocol Engine (no X.25)

CMX218

© 1999 Consumer Microcircuits Limited

17

D/218/1

© 1999 Chiron Technology Limited

1.5.6

Data Configuration

1.5.6.1 Hayes Command Set

The following Hayes commands are supported:

A

- Answers a call

D

- Dial

E

- Echo Hayes commands or not

H

- Hang-up

I3

- Firmware part number

Q

- Result code display

V

- Result code form

X

- Result code set

&C

- Carrier detect

&D

- Data terminal ready

&F

- Load factory default

&K

- Flow control

&V

- View active and stored profiles

&Z

- Store directory number

Valid Hayes commands are responded to with an 'OK' result code. Invalid commands are rejected with

an 'ERROR' result code.

If when entering an AT command, no command or register name suffix is supplied, a suffix of zero is

assumed. If when changing a register value, no value is supplied a value of zero or an empty string is

assumed: eg ATS0=<CR> is equivalent to ATS0=0<CR>.

If a data call is active when a command is entered, the command will be processed. The ATO

command will respond ‘OK’, but will not then enter the data state: it will stay in the command state.

Where commands set a parameter, these are saved in external EEPROM if they are entered correctly.

The CMX218 will auto-baud and auto-parity on Hayes commands at the following speeds:

9600 bps

19200 bps

38400 bps

57600 bps

115200 bps

The auto-bauding process looks for the characters ‘AT’ or ‘at’ either as 8 bits no parity or 7 bits even,

or odd, parity. An error in the auto-bauding process results in auto-bauding being restarted.

After auto-bauding successfully, the CMX218 waits to receive a complete Hayes command line before

processing it. Embedded spaces are ignored and the case (upper or lower) of characters after the

‘AT’ does not matter. The command line is terminated by <CR>, by 250 characters (not including the

‘AT’) or by a time-out (from successful auto-bauding on an ‘AT’) of 180 seconds.

All characters in the Hayes command, including the ‘AT’ and <CR> terminator are echoed (if E1 is set)

by the CMX218 as they are sent by the DTE.

Receipt of a back space will cause the CMX218 to send a "back space, space, back space" sequence

of characters to the DTE to allow the terminal to clear its screen of the last character. Also the last

character received will be discarded unless the last characters received were the ‘AT’ used for auto-

bauding, ie the ‘AT’ is never deleted.