Measurement Computing Personal488 rev.3.0 For DOS & Windows 3.Xi - Manual (Page 135)

8N. Operating Modes II. SOFTWARE GUIDES - 8. Driver488/DRV
II-120 Personal488 User’s Manual, Rev. 3.0
should be used in the Interrupt Service Routine to prevent re-interruption by an indicator which has not
been reset.
Not System Controller Mode
If Driver488/DRV is not configured as the System Controller, then at power on, it is a bus Peripheral.
It might use a program like the one previously described to communicate with the Active Controller.
When Driver488/DRV is not the System Controller and not the Active Controller (
*SC*CA ), the
available bus commands and their actions are:
Command Action
ENTER Receive data from a bus device as directed by the Active Controller.
OUTPUT Send data to bus devices as directed by the Active Controller.
REQUEST Set own Serial Poll request (including Service Request) status.
SPOLL Get own Serial Poll request status.
Active Controller, Not System Controller Mode
If the Active Controller passes control to the Driver488/DRV, then it becomes the new Active
Controller. This can be detected by the
STATUS command or as an ARM ed interrupt. As an Active
Controller, but not the System Controller, the available bus commands and their actions are:
The various ARM conditions and their descriptions are provided in the following table:
ARM Condition Description
SRQ The internal Service Request state is set. See the SPOLL command in
“Section III: Command References” for more information.
Peripheral Driver488/DRV is in the Peripheral ( *CA ) operating mode.
Controller Driver488/DRV is the Active Controller ( CA ).
Trigger Driver488/DRV, as a Peripheral, has received a TRIGGER bus command.
Clear Driver488/DRV, as a Peripheral, has received a CLEAR bus command.
Talk Driver488/DRV is in the Talk state and can OUTPUT to the bus.
Listen Driver488/DRV is in the Listen state and can ENTER from the bus.
Idle Driver488/DRV is in neither the Talk nor Listen state.
Bytein Driver488/DRV has been received a byte from the IEEE 488 bus.
Byteout Driver488/DRV can output a byte to the IEEE 488 bus.
Error Driver488/DRV has detected an error condition.
Change An Address Change has occurred, that is, a change between Peripheral
and Controller, or among Talk , Listen , and Idle has occurred.
This is, perhaps, the most useful interrupt in the Peripheral mode.
Command Action
ABORT Assert Attention and send My Talk Address to stop any bus transfers.
LOCAL Send Go To Local to selected devices.
LOCAL LOCKOUT Prevent local (front-panel) control of bus devices.
CLEAR Clear all or selected devices.
TRIGGER Trigger selected devices.
ENTER Receive data from a bus device.
OUTPUT Send data to bus devices.
PASS CONTROL Give up control to another device which becomes the Active Controller.
SPOLL Serial Poll a bus device, or check the Service Request state.
PPOLL Parallel Poll the bus.
PPOLL CONFIG Configure Parallel Poll responses.
PPOLL DISABLE Disable the Parallel Poll response of selected bus devices.
PPOLL UNCONFIG Disable the Parallel Poll response of all bus devices.
SEND Send low-level bus sequences.
RESUME Unassert Attention. Used to allow Peripheral-to-Peripheral transfers.