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Operating the Meter Using the Computer Interface
Service Requests (IEEE-488 Only and Status Registers
5
5-13
A measurement is triggered while the input is greater than +3 V. A method for using
DTR (pin 4) and an external switch to trigger a measurement is shown in Figure 5-2.
• Send the IEEE-488 GET interface message (IEEE-488 Operations).
Table 5-3. Trigger Type
Type Trigger Rear Trigger Settling Delay
1
2
3
4
5
Internal
External
External
External
External
Disabled
Disabled
Disabled
Enabled
Enabled
—
Off
On
Off
On
Table 5-4. RS-232 and IEEE-488 Reading Transfer Rates
Readings per Second
RATE
Internal Trigger Operation
(Trigger 1)
Internal Trigger Operation
(Trigger 4)
Slow
Medium
Fast
2.5
4.5
4.5
1.5
2.4
3.8
DTR (PIN 4)
RX (PIN 2)
TRIGGER TO µP
aam20f.eps
Figure 5-2. External Trigger Using Receive Pin (RX) of RS-232 Interface
Service Requests (IEEE-488 Only and Status Registers
Service requests let a meter on the IEEE-488 bus get the attention of the host. Service
requests are sent over the service request (SRQ) bus line.
Note
If the meter is in the remote state without front panel lockout (i.e., REMS), a
service request can be sent from the front panel by pressing U.
If more than one instrument on the bus is capable of sending service requests, the host can
determine which instrument made the request by taking a "serial poll." Each instrument on