Measurement-computing Micro 488/EX rev.2.1 Manual do Utilizador descarregar pdf (Página 129)

Section 5 Command Descriptions

5.59

PPOLL CONFIG or PPC

PPOLL

CONFIG

(Parallel Poll Configure) configures the Parallel Poll response of

a specified bus device. Not all devices support Parallel Polling and, among those that

do, not all support software control of their Parallel Poll response. Some devices are

configured by internal switches.

The Parallel Poll response is set by a four-bit binary number (S P2 P1 P0),

response

. The most significant bit of

response

is the Sense (S) bit. The Sense bit

is used to determine when the device will assert its Parallel Poll response. Each bus

device has an internal individual status (

ist

). The Parallel Poll response will be asserted

when this

ist

equals the Sense bit value.

ist

is normally a logic "1" when the device

requires attention, so the S bit should normally also be a logic "1". If the S bit is "0"

then the device will assert its Parallel Poll response when its

ist

is a logic "0", i.e. it

does not require attention. However, the meaning of

ist

can vary between devices, so

refer to your IEEE bus device documentation.

The remaining 3 least significant bits of

response

, P2, P1, and P0, specify

which DIO bus data line will be asserted by the device in response to a Parallel Poll.

These bits form a binary number with a value from 0 through 7, specifying data lines

DIO1 through DIO8, respectively.

SYNTAX PPOLL CONFIG addr;response

PPOLL C addr;response

PPC addr;response

addr

is a bus address.

response

is the decimal equivalent of the four binary bits S, P2,

P1, and P0.

RESPONSE None

MODE CA

1 2 ... 124 125 126 127 128 129 130 131 132 133 134 ... 217 218

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