Gpib Remote Interface Description - Aeroflex NAV 2000R Operation Manual

3.6.1 GPIB REMOTE INTERFACE DESCRIPTION

The NAV 2000R will buffer incoming command characters until the GPIB controlling host signals an EOI
(end of string) interrupt with the last data character. The NAV 2000R is capable of handling up to 4096
command characters at one time. If an incoming command string exceeds the 4096 byte mark, which
primarily occurs with binary downloads, the NAV 2000R will truncate extra characters.
A maximum of 511 bytes of characters can be returned by the NAV 2000R at once. At present, all GPIB
commands return only a few bytes of information. Therefore, 32 bytes are sufficient.
GPIB commands sent to the NAV 2000R are not case sensitive. That is, both lower and upper case
characters are treated the same. Any "white space" characters are ignored, allowing the space character
to be used freely to promote readability. The <CR> carriage return and <LF> line feed characters are
treated as "white space" characters and are ignored.
All commands may be compounded by using the semicolon ';' character to separate each individual
command. This allows the controller's application to send several setup commands at once if desired.
However, if the controller requests the NAV 2000R to return multiple information, the last requested
information will be the only data available.
After the GPIB controller sends a command string to the NAV 2000R, it may request a response from the
NAV 2000R at anytime. A list of the returned data for the given conditions are as follows:
1> If the last command sent was unrecognizable, the NAV 2000R will return the character '?'.
2> If the last command sent was recognized and, by definition, returns a value, that value will be
returned by the NAV 2000R.
3> If a recognized command does not, by definition, return a value, the character '*' will be
returned.
4> The '#' character is returned when a recognized command contains invalid parametric data
(in the form of arguments). The parametric data may be unrecognizable or may just be out of
range.
5> The '!' character is returned when a recognized command received is illegal for the current
given NAV 2000R mode of operation.
6> The '%' character is returned if a NAV 2000R fatal error is in existence. This can occur with
power up self test failures of major NAV 2000R internal systems.
If a command in the middle of a compound command string causes an error, ('?', '#', '!', '%' types),
remaining commands within the command string will be ignored to allow notification to the controller that
it's application has an unwanted condition present. This occurs during application debug stages due to
syntax type errors.
NAV 2000R SIGNAL GENERATOR - REV. 0 – JULY 26, 2007 - PG 3-26
Aeroflex Operation Manual