ICS ELECTRONICS 4809A, Instruction Manual

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A-11
A
Commands start with an asterisk. Commands that end with a question mark
are queries. Query responses can be an ASCII number or an ASCII string.
Other numerical formats are legal as long as the device supports the required
ASCII format. Table A-2 lists the IEEE 488.2 Common Commands.
A1.2.4 IEEE 488.2 Differences From IEEE 488.1
The user who is familiar with the older 488.1 devices should take the fol-
lowing differences into account when programming a 488.2 device.
A 488.2 device outputs the Status Byte Register contents plus the RQS bit
in response to a serial poll. The RQS bit is reset by the serial poll. The
same 488.2 device outputs the Status Byte Register contents plus the MSS
bit in response to a *STB? query. The MSS bit is cleared when the condi-
tion is cleared.
488.2 restricts the Device Clear to only clearing the device's buffers and
pending operations. It does not clear the Status Reporting Structure or the
output lines. Use *CLS to clear the Status Structure and *RST or *RCL
to reset the outputs.
488.2 commands are really special data messages and are executed by the
device's parser. Always allow sufficient time for the parser to execute the
commands before sending the device a 488.1 command. i.e. a Device Clear
sent too soon will erase any pending commands and reset the parser.
Enable Register values are only saved and restored if the *PSC command is
0. A *PSC command of 1 causes zeros to be loaded into the enable registers
when the unit is next reset or powered on.