30
Unnnnn COMMAND
The UNLOCK command allows access to the SYSTEM commands. This set of commands
are intended for diagnostic and configuration purposes and have the power to erase or
modify the contents of the memory. The U command must be sent with the correct KEY
parameter before these commands may be used. The KEY value for these commands is
9999.
A lower level of key protection is provided for the "!" command, to avoid accidental
errors. Any non-zero value will unlock this command.
Two additional special key values are significant. These are intended specifically to allow
a GATEWAY MASTER instrument to be used to load RAM data (via a "Y" command) to a
SLAVE instrument, without the data being "obeyed" as commands, by the MASTER. A
value of U1234 puts the MASTER to SLEEP, until the specific sequence U4321 is detected.
Whilst it is asleep, all data received via the GPIB interface is passed on to the slave but
ignored by the master.
Thus the allowed values of U are:
U0
LOCKED (Power-up Default)
U1
"!" COMMAND UNLOCKED
U1234 SLEEP
U4321 WAKE
UP
U9999
"Y" COMMAND UNLOCKED
V COMMAND
The VERSION command requires no parameters. It returns a message indicating the
instrument type and firmware version number.
Wnnnn COMMAND
The WAIT command sets a delay interval before each character is sent from ILM via the
computer interface. This allows ILM to communicate with a slow computer with no input
buffering. The parameter nnnn specifies the delay in milliseconds. It defaults to zero at
power-up.
(N.B. the W command does not reduce the rate at which ILM can accept data from
computer.)
X COMMAND
The EXAMINE command allows the computer to read the current ILM STATUS. It requires
no parameters and will return a message string of the form:
XabcSuuvvwwRzz
where "a" "b" and "c" are three decimal digits defining the use of the three channels
and "uu", "vv" and "ww" are three pairs of hexadecimal (base 16) digits indicating the
current status of the three channels. A further pair of hexadecimal digits "zz" indicate
the current status of the logic level outputs (and relays if fitted). The significance of the
various sections of the status message is described in more detail, with examples, in
section 8.2 below.
