American Magnetics 286 Multi-Sensor Liquid Level Instrument (CE-Marked) - Manual (Page 83)

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Remote Interface Reference
RS-232/422 Configuration
5.2.6.1 Using the *OPC Command
The *OPC command is executed within the normal command queue. Upon
completed execution of the *OPC command, the “Operation Complete” bit
(bit 0) of the Standard Event register will be set.
If the operator has so configured the Standard Event and Status Byte
enable registers, the
*OPC command can generate a service request when
execution completes (see Figure 5-1). If using the serial port, the *OPC?
query is a better alternative since a response is returned directly to the
requesting communications interface.
An example of a sequence of commands using the *OPC command to
handshake is the following:
PERCENT; CH1:ALARM:HI 90.0; CH1:ALARM:LO 10.0; *OPC;
The above example sets the remote units to percent, the Channel 1 “HI”
alarm to 90.0%, the Channel 1 “LO” alarm to 10.0%, and sends
*OPC as the
4th command for determining when execution all of the commands
(including
*OPC ) has completed.
5.2.6.2 Using the *OPC? Query
The *OPC? query is similar to the *OPC command, but instead of setting
the “Operation Complete” bit of the Standard Event register, the *OPC?
query returns a “1” (plus termination characters) to the requesting remote
interface when executed. Using
*OPC? is often the most straightforward
solution for determining completed command execution. It is also
unambiguous since the result is returned directly to the requesting remote
communication interface.
5.2.7 Remote Units
The Model 286 supports a remote units setting that is maintained
separately from the units selected via the front panel keypad. The remote
units setting is retained between power-ups. If the
PERCENT command is
sent to the remote interface, the remote units for both remote interfaces is
set to percent. All alarm values should then be sent as a percent value, and
all return level data and alarm queries are returned in units of percent.
The UNITs? query returns the currently selected remote units (e.g. the
percent setting would return 0,”PERCENT”) .
5.3 RS-232/422 Configuration
The Model 286 allows the baud rate of the RS-232/422 interface to be
configured by the user. See the menu description in paragraph 4.3.12.3 on