Measurement Computing Micro 488/EX rev.2.1 - Manual (Page 82)

Section 5 Command Descriptions
5.12
ARM
The ARM command allows the Micro488/EX to automatically send event
messages to the serial host when one or more of the specified events occur. The event
messages that are returned are the same non-abbreviated strings as those used to
program the events.
There are two types of events, level sensitive and edge sensitive. Level sensitive
events, such as SRQ, will be reported every time they are ARMed while the event
condition persists. Usually, some action must be taken (eg SPOLL) to clear the
condition prior to re-issuing the ARM. Edge sensitive events, such as TRIGGER, are
cleared when reported.
Regardless of the event sensitivity, the ARM command must be re-sent after the
event message is reported to re-activate the ARMed condition. The optional events
include…
SRQ The event message 'SRQ' is returned to the serial host when the state
of the Service Request Bus Line is detected in the asserted state.
This event is level sensitive. If the condition exists at the time the
ARM
SRQ command is issued, the Micro488/EX will return the event
message immediately. If the ARM command is issued without any
specified events, the SRQ event is assumed. This provides upward
compatibility with the Micro488/EX in previous Micro488 systems.
PERIPHERAL The event message 'PERIPHERAL' is returned to the serial host
when the Micro488/EX is forced from the Controller Active State
(*SC•CA) to the Peripheral State (*SC•*CA) by receipt of IFC from
the System Controller. This can be useful in detecting receipt of IFC
when in the *SC•CA state. This event is edge sensitive.
CONTROLLER The event message 'CONTROLLER' is returned to the serial host
when the Micro488/EX receives control of the bus and transitions
from the Peripheral State (*SC•*CA) to the Controller Active State
(*SC•CA). This occurs when the Take Control interface message is
received by the Micro488/EX. This event is edge sensitive.