Measurement-computing Serial488A Manuel d'utilisateur télécharger pdf (Page 35)

3.1

Controller Operation

3.1 Controller Mode (Serial to IEEE) Operation

The

IEEE Controller

mode allows a serial RS-232 or RS-422 host device to

send data to a single IEEE bus peripheral or to multiple peripherals if they occupy the

same bus address. Applications include interfacing a listen-only or addressable IEEE

printer/plotter to a serial printer port.

Once the

Serial488A

has initialized itself after power-on, it waits for serial

input data. When received, it addresses the selected IEEE device to listen with the

following bus sequence:

ATN•UNL,MTA,LAG,*ATN

The data received from the serial host is placed into a circular serial input buffer.

Simultaneously, characters are removed from that buffer and sent to the IEEE bus

device. The serial terminator(s), if present, are not sent. Instead, the IEEE terminators

are substituted and sent in their place.

So long as the serial input buffer is not empty, the

Serial488A

will continue to

send data from it to the IEEE bus device. If the serial input buffer becomes emptied,

the

Serial488A

will command the IEEE bus device to talk if one of the talk back

features is enabled. This allows the

Serial488A

to be used as a controller with

devices, such as plotters or instruments, that return status and other information to the

host computer.

When the

Serial488A

addresses the IEEE bus device to talk it uses the following

bus sequence:

ATN•UNL,MLA,TAG,*ATN

The

Serial488A

then accepts data from the IEEE device and returns it to the host

until the last selected IEEE terminator is detected. The IEEE bus terminators are

replaced by the serial terminators and these are then sent to the serial host.

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Measurement-computing Serial488A Manuel d'utilisateur Page 35