Modem Emulation AT Command Set Function Result

Application AT Com-	Digi Device Server Response	Notes
mand

ATH	NO CARRIER response sent	Disconnect AT command is sent-Digi device server
ATH	NO CARRIER response sent	responds with NO CARRIER
		responds with NO CARRIER

In the following table, the Digi device server receives a request for a connection.

AT Command	Digi Device Server Response	Notes
	RING	The Digi device server sends a Call Notification

		Manual (ATA) or Auto Answer (ATS0=n) response-the
ATA (or ATS0=n)	CONNECT 115200	Digi device server sends a CONNECT message when
		the TCP session is started

	NO CARRIER	The Digi device server sends a NO CARRIER message
	NO CARRIER	when the remote disconnects
		when the remote disconnects

Originating Calls

To send data to a Digi device server, enter the following information for your application replacing the telephone number with the Digi device server’s IP address and TCP port number. Enter the following command:

ATDT ipaddress:tcp_port#

an example is ATDT 146.135.13.5:50001

Answering Calls

The Digi device server listens on a pre-defined TCP port to receive data. When the Digi device server receives a call notification (RING) through a serial port to begin a TCP connection, it needs to reply with an ATA or a pre-configured Auto-Answer to answer the call.

Note: The TCP ports assigned to the serial ports are as follows:

Serial port 1 listens on TCP port 50001

Serial port 2 listens on TCP port 50002

Serial port 3 listens on TCP port 50003

Serial port 4 listens on TCP port 50004

Disconnecting Calls

The TCP connection disconnects by either dropping the DTR signal on the serial port or sending the escape sequence <P>+++<P> to the Digi device server. <P> represents a one second pause.

Disconnecting Calls-Digi Device Server

The Digi device sends a NO CARRIER response to the serial port when the network connection is dropped.