9 Print Server Operation
9.2.1.1 ASCII Text
Ordinary ASCII characters are entered as they are on the keyboard. The
single exception is the ’Less Than’ character ’<’, which is used for other special functions.
9.2.1.2 ASCII Control Codes
ASCII control codes are entered by their standard name, enclosed
in ’Angle Brackets’, i.e. in ’<’ and ’>’ (Greater Than). Some examples of this are <ESC>, <CR>
or <TAB>.
9.2.1.3 Numeric Codes
Especially binary data must be sent by means of its numeric value. Since
the ’<’ ASCII character has a special function, the only way to use this is the numeric method.
This also applies to printable characters of some Extended ASCII character sets.
The NetCom
+
accept the decimal value, also enclosed in angle brackets. Up to three decimal digits
define the character to send to the printer. The ’<’ is used as <60>, while the <ESC> may also
sent as <027>. The ’>’ may be used directly, however for clarity <62> should be preferred.
9.2.1.4 Modem Control Signals
Via the ‘InitString’ control of RTS and DTR is available. This
manual does not make statements about voltage levels on the signals, these are just set to an active
or inactive state. <RTS+> and <RTS-> activate and deactivate the RTS signal, while <DTR+>
and <DTR-> do the same for DTR.
9.2.1.5 Timing Options
Especially when using Modem Control signals it will be required to hold
them in a given state for a defined amount of time. This may be done by applying a »Pause«-
command in the ‘InitString’. The delay is given as numeric value in milliseconds (msec), preceded
by a ‘P’. So <P50> causes the NetCom
+
to wait 50 msec before proceeding with the next command
or start printing. Up to three digits are possible. If more than 999 msec are required, the Pause-
command must be repeated.
Please note: The delay is not executed as an exact time. NetCom
+
guarantees to wait at least the
required amount of time. The smallest delay possible is 10 msec, due to internal handling of date
and time.
9.2.2 Reset Example
For example here is a hypothetical serial printer. The serial port operates at 1200 bps, 7 bit and
even parity and 1 stop bit. For Reset the printer requires the command "<ESC>@0" sent with
DTR and RTS off. When the data is transmitted, DTR must be on, and 50 msec later RTS must
also be on.
Each character sent is 10 bits long, including the start bit. At 1200 bps each character needs
8.3 msec for transmission. So the transmission lasts for 25 msec. To be sure the control signals are
inactive, an extra delay is applied after change of signals. The resulting string would be <RTS-
><DTR-><P10><ESC>@0<P35><DTR+><P50><RTS+> The delay of 35 msec after the
command string "<ESC>@0" shall ensure, all data is completely transmitted to the printer.
September 2016
NetCom Plus User Manual
106
