Specifications

Chapter 4 – Serial Interface Control Commands
Multi-Tech Systems, Inc. AT Commands for EDGE Modems (S000371B) 51
Chapter 4. Serial Interface Control
Commands
The AT Commands described in this chapter allow the external application to determine various settings related to
the Multi-Tech wireless modem’s serial interface.
4.1 AT\Q Flow Control
Exec Command Syntax: AT\Q[<n>]
Response: OK
If RTS/CTS flow control is not supported by interface and <n> is 2 or 3:
ERROR
Parameter Description:
<n>
0 Disable flow control. Default.
1 XON/XOFF software flow control
2 Only CTS by DCE (TA)
3 RTS/CTS hardware flow control
Recommended for the following procedures: incoming or outgoing data calls, fax calls, MUX mode.
Often, the initialization routine of Fax programs includes enabling RTS/CTS handshake, eliminating the need
to issue AT\Q3 once again.
Notes:
• When using XON/XOFF flow control (AT\Q1) in online mode, +++ should not be used while the data transmission
is paused with XOFF. Before entering the command mode with +++ the paused transmission should be resumed
using the XON character.
• Flow Control can be set by also using AT+IFC.
4.2 AT&C Set Circuit Data Carrier Detect (DCD)
Function Mode
Description: The AT&C command determines how the state of circuit 109 (DCD) relates to the
detection of received line signal from the distant end.
Exec Command Syntax: AT&C[value]
Response: OK
Parameter Description:
<value>
0 DCD line is always ON. Default.
1 DCD line is ON in the presence of data carrier only.
4.3 AT&D Set Circuit Data Terminal Ready (DTR)
Function Mode
Description: The AT&D determines how the TA responds when circuit 108/2 (DTR) is changed from
ON to OFF during data mode.
Exec Command Syntax: AT&D[<value>]
Response: OK
Parameter Description:
<value>
0 TA ignores status of DTR. Default.
1 ON->OFF on DTR: Change to command mode while retaining the connected call.
2 ON->OFF on DTR: Disconnect data call, change to command mode. During state DTR = OFF auto-answer
is off.