455U-D Radio Modem
User Manual
Page
76
©
Jan 2016
AT&C
Data Carrier Detect (DCD) Control.
&C0
DCD Always on.
&C1
DCD High when connected (Acknowledged Mode) or when online
(Unacknowledged mode). Low otherwise.
&C2
DCD Always on, Pulses low on Disconnect (Acknowledged Mode) or on Hangup
(Unacknowledged mode).
AT&D
Data Terminal Ready (DTR) Behavior. The host controls DTR. This command
controls how the modem reacts to the state of DTR.
&D0
Modem ignores DTR, and acts as if it is asserted.
&D1
If the host lowers DTR, the modem returns to command mode, but does not
disconnect.
&D2
If the host lowers DTR, the modem disconnects and returns to command mode.
&D3
If the host lowers DTR, the modem disconnects and goes to low power mode.
Raising DTR will cause the modem to dial if the fixed line settings are correct
(&L1).
AT&E
CRC Error Checking
&E0
Disable CRC Error Checking
&E1
Enable CRC Error Checking for RS-232 port
&E2
Enable CRC Error Checking for RS-485 port
&E3
Enable CRC Error Checking for both RS-232 and RS-485 port
AT&F
Restore Factory Defaults. This function is also available from the external DIP
Switch.
AT&H
Broadcast Repeater Hops Setting – Set the number of hops for a message to
activate the broadcast repeater function (AT&R).
&H0
Don’t repeat messages to the “Wildcard” address, and don’t copy repeated
messages out the local serial port, regardless of the AT&R setting.
&H1
Perform the action specified by the AT&R setting when the wildcard address is
the first Store&Forward address, and the message has completed one hop.
&H2
Perform the action specified by the AT&R setting when the wildcard address is
the second Store&Forward address, and the message has completed two hops.
&H3
.. &H6
Repeat Messages when the wildcard address is the third (.. sixth) Store&Forward
address, and the message has completed three (..six) hops.
AT&K
RS-232 Serial port Flow Control Configuration. Flow control options are: none,
CTS/RTS and XON/XOFF.
In Acknowledged mode, flow control passes across the modem link, as the local
buffers become full, then back to the remote host device as the remote modem’s