PTT When TX On
A T & P T T x
Turns on /off “PTT When TX On” option. For x = 0 modem PTT
relay doesn’t react on carrier On/Off changes. For x = 1 PTT relay is
switched On when carrier is On, and switched Off when carrier if Off.
This relay may be used to turn On external transmission equipment (for
example radio trasmitters).
Use SQ Input
A T & S Q x
Turns on /off “Use SQ Input” option. For x = 0 modem DCD (CD on
RS-232C and front panel LE diode) follows in-channel carrier presence
changes. For x = 1 modem DCD (CD on RS-232C and front panel LE
diode) follows SQ input state changes. SQ input may be used for
indication of in-channel carrier presence signalization when external
reception equipment is used (ex. radio receivers).
Use
DTR
A T & D T R x
Turns on /off “Use DTR” option. For x = 0 state of DTR input is
overriden and assumed that is always set to 1. For x = 1 DSR signal is
copied to DTR signal. Modem works properly only when DTR = 1.
Carrier
control
A T & C C x
Selects transmission carrier control mode. For x=0 transmission is
always on and carrier is permanent. For x = 1 transmission is active
only if RTS = 1 (Data Terminal Equipment requires to send). For x = 2
transmission is active only if there is data in transmission buffer. This
mode is called DOX - Data Operated Xmission.
Important:
If half-duplex mode is configured, it is obligatory to set “Transmission
on RTS” or DOX option. Otherwise, modem would permanently
transmit on a half-duplex line, disabling line access to other modems
connected to it.
Character
Format
A T & C F d p s
Selects the number of data bits, parity and stop bits. Valid range for
data bits is 5 to 8; for parity is N(one), E(ven), O(dd); for stop bits is 1
or 2. For FSK modulations due to restrictions associated with logic
regeneration in asynchronous mode, the modem uses resynchronisation
procedure at reception. In this mode the character format is between 5
and 9 useful bits, enclosed with 1 start and 1 stop bit. The parity bit,
and additional stop bit is considered as a data bit and will be
transmitted without processing, therefore for example, transmission
and reception of 9N1 format is possible with FSK modulations with
8E1 or 8O1 settings.
Example:
AT&CF8N1 command line sets format: 1 start / 8 data / 1 stop bit.
Modem responds with “OK” message.
IG202T-R38 User Manual v1.3
, Rev. date: 16 November, 2009
12
