488 CONTROLLER
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The Operating Mode (C or P) indicates whether or not the 488 Controller is the Active Controller. If the
488 Controller Passes Control to another device, then the Operating Mode indicator will change from “C” to
“P.” When the 488 Controller regains control, then the indicator will again be “C.” If the 488 Controller is
not the System Controller, then it will initially be a Peripheral, and thus the indicator will be “P.” It will, of
course, become “C” when the 488 Controller receives control from the Active Controller.
The Bus Address is the IEEE bus device address assigned to the 488 Controller by the internal hardware
switch.
The Address Change (G0, G1) indicator is set whenever the 488 Controller transitions from the idle state to
a Talker or Listener, or from a Talker or Listener state to an idle state. It will not indicate when a change is
made from a listener to a talker or a talker to a listener. The address change is reset when STATUS 1 is read.
The Addressed State is the current talker/listener state of the 488 Controller. As a Peripheral, the 488
Controller can check this status to see if it has been Addressed to Talk or Addressed to Listen by the Active
Controller. In this way the desired direction of data transfer can be determined.
The Service Request indicator reflects the external SRQ status. If the SRQ line is asserted, S1 will be
reported. If it is unasserted, S0 will be reported.
The Error Code is 00 when no error has occurred. If it is nonzero, then the appropriate error message is
appended to the STATUS 1 response. For more details about the individual errors, refer to
Appendix B
. The
Error Code is reset to 00 when STATUS is read.
The Triggered (T0, T1) and Cleared (C0, C1) indicators are set when, as a Peripheral, the 488 Controller
has received a GET (Group Execute Trigger) or SDC/DCL (Selected Device Clear/Device Clear) bus
command. These two indicators are cleared when STATUS1 is read.
By issuing the STATUS 2 command, only the numeric error value is returned to the serial output port. If no
error has occurred, the value sent is 0. The error condition is clear when reported.
SYNTAX
STATUS [;][number] or ST [;][number]
number is 0 to 2. If not specified, 0 is assumed.
RESPONSE
Character string as described previously
MODE
Any
BUS STATES
None
EXAMPLES:
PRINT#1,"STATUS"
Read the 488 Controller status
INPUT#1,A$
PRINT A$
and display it.
CONTROLLER 10
Example of displayed STATUS 0
PRINT#1, "STATUS1"
Read the 488 Controller extended status and display it.
INPUT#1,A$
PRINT A$
C 10 G0 I S0 E00 T0 C0 OK
Example of STATUS 1
PRINT#1,"STATUS2"
Read the 488 Controller error status and display it.
INPUT#1,A
PRINT A
0
Example of displayed STATUS 2
