Measurement-computing Digital488 Bedienungsanleitung PDF herunterladen (Seite 38)

Section 3 Command Descriptions

3.8

Data Ready Rn

The

Data Ready

command enables digital input data to be latched. When used in

conjunction with the

Service Request

(

) command, the

External Data Ready

line

can both latch the input data and signal the controller that new data is available.

In the default mode (

) data is read when the

Digital488

is addressed to talk. In

the

mode, it will wait for the selected

External Data Ready

(

EDR

) transition before

reading the data and formatting it for output. If the

Digital488

is addressed to talk before

EDR

is asserted, the bus will hang up until the

EDR

pulse occurs. Once

EDR

is asserted

the data will remain latched until the interface is addressed to talk and the data is read by

the controller. If

EDR

transitions again before the previous

EDR

buffered data has been

output, the

Digital488

will generate an

EDR Overrun

error and ignore the

EDR

read

request.

After output in the

through

formats, the

Digital488

must be re-addressed to

talk to perform subsequent buffered output of

EDR

captured data.

EDR

cannot be used

to capture data in the

high speed binary format

The

EDR

signal must be at least 1 microsecond wide and should have a rise and

fall time of less than 1.0 microsecond. The

EDR

line defaults to rising-edge sensitive, but

can be changed to falling-edge sensitive with the

Invert

command (

I32

Data is not latched, and is read whenever the

Digital488

is addressed to talk

Data is latched on an

EDR

transition

Example:

CLEAR 718

reset the

Digital488

OUTPUT 718;"R1X"

data is only read after a rising-edge

signal is applied to the

EDR

line

1 2 ... 33 34 35 36 37 38 39 40 41 42 43 ... 82 83

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