gpib函数

5. GPIB protocol

5.1. GPIB command bytes

The meaning and values of the possible GPIB command bytes are as follows:

Table 12. GPIB command bytes

byte

(hexadecimal)

0x1

0x4

0x5

value

name

GTL

SDC

PPConfig (also 'PPC' on

non- powerpc

architectures)

GET

TCT

LLO

DCL

PPU

SPE

SPD

MLA0 to MLA30

description

Go to local

Selected device clear

Parallel poll configure

0x8

0x9

0x11

0x14

0x15

0x18

0x19

0x20 to 0x3e

0x3f

0x40 to 0x5e

0x5f

0x60 to 0x6f

Group execute trigger

Take control

Local lockout

Device clear

Parallel poll unconfigure

Serial poll enable

Serial poll disable

My

(primary)

listen

address 0 to 30

UNL

Unlisten

MTA0 to MTA30

My

(primary)

talk

address 0 to 30

UNT

Untalk

MSA0

to

MSA15,

also

When following a talk or

PPE

listen

address,

this

is

'my

secondary

address'

0

to

15. When

following

a

parallel

poll

configure,

this

is

'parallel

poll

enable'.

For parallel poll

enable,

the

least

significant

3

bits

of

the

command

byte

specify

which

DIO

line

the

device

should

use

to

send

its

parallel

poll

response.

The

fourth

least significant bit (0x8)

0x70 to 0x7d

0x7e

5.2. GPIB bus lines

indicates

the

'sense'

or

polarity

the

device

should

use

when

responding.

MSA16

to

MSA29,

also

When following a talk or

PPD

listen

address,

this

is

'my

secondary

address'

16 to 29. When following

a

parallel

poll

configure,

this

is

'parallel

poll

disable'.

MSA30

My

secondary

address

30

Physically, the GPIB bus consists of 8 data lines, 3 handshaking lines, and 5

control

lines

(and

8

ground

lines).

Brief

descriptions

of

how

they

are

used

follow:

Table 13. GPIB bus lines

bus line

DIO1 through DIO8

description

Data

input/output

bits.

These

8

lines are used to read and write

the 8 bits of a data or command

byte

that

is being

sent

over the

bus.

End-or-identify.

This

line

is

asserted

with

the

last

byte

of

data

during

a

write,

to

indicate

the

end

of

the

message.

It

can

also be asserted along

with the

ATN

line

to

conduct

a

parallel

poll.

Data

valid.

This

is

a

handshaking line, used to signal

that

the

value

being

sent

with

DIO1-DIO8

is

valid.

During

transfers

the

DIO1-DIO8

lines

are

set,

then

the

DAV

line

is

asserted after a delay called the

'T1 delay'. The T1 delay lets the

pin number

DIO1

to

DIO4

use

pins 1 to 4, DIO5 to

DIO8

use

pins

13

to 16

5

EOI

DAV

6

NRFD

NDAC

IFC

SRQ

ATN

REN

data lines settle to stable values

before they are read.

Not

ready

for

data.

NRFD

is

a

handshaking

line

asserted

by

listeners to indicate they are not

ready

to

receive

a

new

data

byte.

Not

data

accepted.

NDAC

is

a

handshaking

line

asserted

by

listeners

to

indicate

they

have

not

yet

read

the

byte

contained

on the DIO lines.

Interface

clear.

The

system

controller can assert this line (it

should

be

asserted

for

at

least

100

microseconds)

to

reset

the

bus

and

make

itself

controller-in-charge.

Service request. Devices on the

bus

can

assert

this

line

to

request

service

from

the

controller-in-charge.

The

controller

can

then

poll

the

devices

until

it

finds

the

device

requesting service, and perform

whatever action is necessary.

Attention.

ATN

is

asserted

to

indicate

that

the

DIO

lines

contain

a

command

byte

(as

opposed to a data byte). Also, it

is

asserted

with

EOI

when

conducting parallel polls.

Remote enable. Asserted by the

system

controller,

it

enables

devices

to

enter

remote

mode.

When REN is asserted, a device

will

enter

remote

mode

when

it

is

addressed

by

the

controller.

When

REN

is

false,

all

devices

will

immediately

return

to

local

mode.

7

8

9

10

11

17

ibwrt

Name

ibwrt -- write data bytes (board or device)

Synopsis

class=FUNCSYNOPSISINFO

#include

int ibwrt(int ud, const void *data, long num_bytes);

Description

ibwrt() is used to write data bytes to a device or board. The argument ud can

be either a device or board descriptor. num_bytes specifies how many bytes

are written from the user-supplied array data. EOI may be asserted with the

last

byte

sent

or

when

the

end-of-string

character

is

sent

(see

ibeos()

and

ibeot()). The write operation may be interrupted by a timeout (see ibtmo()), the

board receiving a device clear command, or receiving an interface clear.

If ud is a device descriptor, then the library automatically handles addressing

the

device

as

listener

and

the

interface

board

as

talker,

before

sending

the

data bytes onto the bus.

If ud is a board descriptor, the board simply writes the data onto the bus. The

controller-in- charge must address the board as talker.

After the ibwrt() call, ibcnt and ibcntl are set to the number of bytes written.

Return value

The value of ibsta is returned.

ibdev

Name

ibdev -- open a device (device)

Synopsis

class=FUNCSYNOPSISINFO#include

ib/ib.h>

int ibdev(int board_index, int pad, int sad, int timeout, int send_eoi, int eos);

Description

ibdev() is used to obtain a device descriptor, which can then be used by other

functions

in

the

library.

The

argument

board_index

specifies

which

GPIB

interface board the device is connected to. The pad and sad arguments specify

the GPIB address of the device to be opened (see

ibpad() and ibsad()). The

timeout for io operations is specified by timeout (see

ibtmo()). If send_eoi is

nonzero, then the EOI line will be asserted with the last byte sent during writes

(see

ibeot()).

Finally,

the

eos

argument

specifies

the

end-of-string

character

and whether or not its reception should terminate reads (see ibeos()).

Return value

If

sucessful,

returns

a

(non-negative)

device

descriptor.

On

failure,

-1

is

returned.

ibcnt and ibcntl

Name

ibcnt and ibcntl -- hold number of bytes transferred, or errno

Synopsis

class=PROGRAMLISTING

#include

volatile int ibcnt;

volatile long ibcntl;

Description

ibcnt and ibcntl are set after IO operations to the the the number of bytes sent

or received. They are also set to the value of errno after EDVR or EFSO errors.

If you wish to avoid using a global variable, you may instead use ThreadIbcnt()

or ThreadIbcntl() which return thread-specific values.

iberr

Name

iberr -- holds error code

Synopsis

class=PROGRAMLISTING

#include

volatile int iberr;

Description

iberr is set whenever a function from the 'traditional' or 'multidevice' API fails

with an error. The meaning of each possible value of iberr is summarized in the

following table:

Table 1. iberr error codes

constant

value

EDVR

0

ECIC

ENOL

EADR

EARG

ESAC

EABO

1

2

3

4

5

6

meaning

A

system

call

has

failed.

ibcnt/ibcntl

will

be

set

to

the

value of errno.

Your

interface

board

needs

to

be

controller-in-charge,

but is not.

You have attempted to write data or command bytes, but

there are no listeners currently addressed.

The interface board has failed to address itself properly

before starting an io operation.

One or more arguments to the function call were invalid.

The interface board needs to be system controller, but is

not.

A read or write of data bytes has been aborted, possibly

ENEB

EDMA

EOIP

ECAP

7

8

10

11

EFSO

EBUS

ESTB

12

14

15

ESRQ

16

ETAB

20

due

to

a

timeout

or

reception

of

a

device

clear

command.

The GPIB interface board does not exist, its driver is not

loaded, or it is not configured properly.

Not

used

(DMA

error),

included

for

compatibility

purposes.

Function call can not proceed due to an asynchronous

IO operation (ibrda(), ibwrta(), or ibcmda()) in progress.

Incapable of executing function call, due the GPIB board

lacking the capability, or the capability being disabled in

software.

File system error. ibcnt/ibcntl will be set to the value of

errno.

An attempt to write command bytes to the bus has timed

out.

One or more serial poll status bytes have been lost. This

can

occur

due

to

too

many

status

bytes

accumulating

(through automatic serial polling) without being read.

The serial poll request service line is stuck on. This can

occur if a physical device on the bus requests service,

but its GPIB address has not been opened (via ibdev()

for example) by any process. Thus the automatic serial

polling

routines

are

unaware

of

the

device's

existence

and will never serial poll it.

This

error

can

be

returned

by

ibevent(),

FindLstn(),

or

FindRQS(). See their descriptions for more information.

If you wish to avoid using a global variable, you may instead use ThreadIberr()

which returns a thread-specific value.

ibsta

Name

ibsta -- holds status

Synopsis

class=PROGRAMLISTING

#include

volatile int ibsta;

Description

ibsta

is

set

whenever

a

function

from

the

'traditional'

or

'multidevice'

API

is

called.

Each

of

the

bits

in

ibsta

has

a

different

meaning,

summarized

in

the

following table:

Table 1. ibsta Bits

bit

DCAS

value

(hexadecimal)

0x1

meaning

used

for

board/device

DCAS

is

set

when

a

board

board

receives

the

device

clear

command

(that

is,

the

SDC

or DCL command byte). It is

cleared

on

the

next

'traditional'

or

'multidevice'

function

call

following

ibwait()

(with

DCAS

set

in

the

wait

mask),

or following

a

read

or

write

(ibrd(),

ibwrt(), Receive(), etc.). The

DCAS

and

DTAS

bits

will

only

be

set

if

the

event

queue

is

disabled.

The

event

queue

may

be

disabled with ibconfig().

DTAS

is

set

when

a

board

board

has

received

a

device

trigger

command

(that

is,

the

GET

command

byte).

It

is

cleared

on

the

next

'traditional'

or

'multidevice'

function

call

following

ibwait()

(with

DTAS

in

the

wait

mask). The

DCAS

and

DTAS bits will only be set if

the event queue is disabled.

The

event

queue

may

be

disabled with ibconfig().

Board

is

currently

board

addressed as a listener.

Board

is

currently

board

addressed as talker.

The ATN line is asserted.

board

Board

is

board

DTAS

0x2

LACS

TACS

ATN

CIC

0x4

0x8

0x10

0x20

REM

LOK

CMPL

0x40

0x80

0x100

EVENT

0x200

SPOLL

0x400

RQS

0x800

SRQI

0x1000

controller-in-charge,

so

it

is

able to set the ATN line.

Board is in 'remote' state.

Board is in 'lockout' state.

I/O

operation

is

complete.

Useful for determining when

an

asynchronous

io

operation

(ibrda(),

ibwrta(),

etc) has completed.

One

or

more

clear,

trigger,

or

interface

clear

events

have

been

received,

and

are

available

in

the

event

queue

(see

ibevent()).

The

EVENT bit will only be set if

the event queue is enabled.

The

event

queue

may

be

enabled with ibconfig().

If

this

bit

is

enabled

(see

ibconfig()), it is set when the

board

is

serial

polled.

The

SPOLL

bit

is

cleared

when

the

board

requests

service

(see

ibrsv())

or

you

call

ibwait()

on

the

board

with

SPOLL in the wait mask.

RQS

indicates

that

the

device

has

requested

service,

and

one

or

more

status

bytes

are

available

for

reading

with

ibrsp().

RQS

will

only

be

set

if

you

have automatic serial polling

enabled (see ibconfig()).

SRQI indicates that a device

connected

to

the

board

is

asserting the SRQ line. It is

only

set

if

the

board

is

the

controller-in-charge.

If

automatic

serial

polling

is

enabled

(see

ibconfig()),

SRQI

will

generally

be

cleared,

since

when

a

device

requests

service

it

board

board

board or device

board

board

device

board

END

0x2000

TIMO

0x4000

will

be

automatically

polled

and then unassert SRQ.

END

is

set

if

the

last

io

board or device

operation

ended

with

the

EOI

line

asserted,

and

may

be

set

on

reception

of

the

end-of- string

character.

The

IbcEndBitIsNormal option of

ibconfig()

can

be

used

to

configure

whether

or

not

END

should

be

set

on

reception

of

the

eos

character.

TIMO indicates that the last

board or device

io operation or ibwait() timed

out.

指示上次输入输出操作或者

ibwait()

函数超时

ERR

0x8000

ERR

is

set

if

the

last

board or device

'traditional'

or

'multidevice'

function

call

failed.

The

global

variable

iberr

will

be

set indicate the cause of the

error.

If you wish to avoid using a global variable, you may instead use ThreadIbsta()

which returns a thread-specific value.

ibask

Name

ibask -- query configuration (board or device)

//

质问

,

询问

,

怀疑

,

疑问

Synopsis

class=FUNCSYNOPSISINFO#include

int ibask(int ud, int option, int *result);

Description

Queries

various

configuration

settings

associated

with

the

board

or

device

descriptor ud. The option argument specifies the particular setting you wish to

query. The result of the query is written to the location specified by result. To

change the descriptor's configuration, see ibconfig().

Table 1. ibask options

option

IbaPAD

IbaSAD

value

(hexadecimal)

0x1

0x2

result of query

used

for

board/device

primary

board or device

board or device

IbaTMO

0x3

IbaEOT

0x4

IbaPPC

0x5

IbaREADDR

0x6

IbaAUTOPOLL

0x7

IbaCICPROT

0x8

IbaSC

0xa

GPIB

address

GPIB

secondary

address

(0

for

none,

0x60

to

0x7e

for

secondary

addresses

0

to

30)

Timeout

setting

for

io

operations

(a number from 0

to

17).

See

ibmto().

Nonzero

if

EOI

is

asserted

with

last

byte

on

writes.

See ibeot().

Parallel

poll

configuration.

See ibppc().

Useless,

included

for

compatibility

only.

Nonzero

if

automatic

serial

polling is enabled.

Useless,

included

for

compatibility

only.

Nonzero

if

board

is

system

board or device

board

device

board

board

board

IbaSRE

0xb

IbaEOSrd

0xc

IbaEOSwrt

0xd

IbaEOScmp

0xe

IbaEOSchar

IbaPP2

0xf

0x10

controller.

See

ibrsc().

Nonzero

if

board

autmatically

asserts

REN

line

when

it

becomes

the

system

controller.

See

ibsre().

Nonzero

if

termination

of

reads

on

reception

of

the

end-of-string

character

is

enabled.

See

ibeos(),

in

particular

the

REOS bit.

Nonzero

if

EOI

is

asserted

whenever

end-of-string

character

is

sent.

See

ibeos(),

in

particular

the

XEOS bit.

Nonzero

if

all

8

bits

are

used

to

match

end-of- string

character.

Zero

if

only

least

significant

7

bits

are

used.

See

ibeos(),

in

particular

the

BIN

bit.

The

end-of-string

byte.

Nonzero if in local

parallel

poll

configure

mode.

Zero

if

in

remote

board

board or device

board or device

board or device

board or device

board

IbaTIMING

0x11

IbaReadAdjust

0x13

IbaWriteAdjust

0x14

IbaEventQueue

IbaSPollBit

0x15

0x16

IbaSendLLO

0x17

parallel

poll

configure mode.

Number

indicating

T1

delay.

1

for

2

microseconds,

2

for

500

nanoseconds,

3

for

350

nanoseconds.

The

values

are

declared

in

the

header

files

as

the

constants

T1_DELAY_2000

ns,

T1_DELAY_500n

s,

and

T1_DELAY_350n

s.

Nonzero

if

byte

pairs

are

automatically

swapped

during

reads.

Nonzero

if

byte

pairs

are

automatically

swapped

during

writes.

Nonzero

if

event

queue is enabled.

Nonzero

if

the

use of the SPOLL

bit

in

ibsta

is

enabled.

Nonzero

if

devices

connected

to

this

board

are

automatically

put

into

local

lockout

mode

when

brought

online

board

board or device

board or device

board

board

board

IbaSPollTime

0x18

IbaPPollTime

0x18

IbaEndBitIsNorm

al

0x1a

IbaUnAddr

0x1b

IbaHSCableLengt

0x1f

h

IbaIst

IbaRsv

0x20

0x21

IbaBNA

0x200

with

ibfind()

or

ibdev().

Timeout

for

serial

polls.

The

value

of

the

result

is

between

0

and

17,

and

has

the

same meaning as

in ibtmo().

Timeout

for

parallel polls. The

value of the result

is

between

0

and

17,

and

has

the

same meaning as

in ibtmo().

Nonzero

if

END

bit

of

ibsta

is

set

on

reception

of

end-of-string

character

or

EOI.

Zero if END bit is

only set on EOI.

Nonzero

if

UNT

(untalk)

and

UNL

(unlisten)

commands

are

automatically

sent

after

a

completed

io

operation

using

this descriptor.

Useless,

included

only

for

compatibility.

Individual

status

bit, a.k.a. 'ist'.

The

current

status

byte

this

board

will

use

to

respond

to

serial

polls.

Board

index

(minor number) of

device

board

board or device

device

board

board

board

device

Iba7BitEOS

0x1000

interface

board

which

is

the

controller-in- char

ge of this device's

GPIB bus.

Nonzero

if

board

board

supports

7

bit

EOS

comparisons. See

ibeos(),

in

particular

the

BIN

bit.

This

is

a

Linux-GPIB

extension.

Return value

The value of ibsta is returned.

ibbna

Name

ibbna -- change access board (device)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibbna(int ud, const char *name);

Description

ibbna() changes the GPIB interface board used to access the device specified

by ud. Subsequent device level calls using the descriptor ud will assume the

device is connected to

the interface board specified by name. If you wish to

specify a device's new access board by board index instead of name, you can

use the IbcBNA option of ibconfig().

The name of a board can be specified in the configuration file .

On success, iberr is set to the board index of the device's old access board.

Return value

The value of ibsta is returned.

ibcac

Name

ibcac -- assert ATN (board)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibcac(int ud, int synchronous);

Description

ibcac() causes the board specified by the board descriptor ud to become active

controller by asserting the ATN line. The board must be controller-in-change in

order to assert ATN. If synchronous is nonzero, then the board will wait for a

data

byte

on

the

bus

to

complete

its

transfer

before

asserting

ATN.

If

the

synchronous

attempt

times

out,

or

synchronous

is

zero,

then

ATN

will

be

asserted immediately.

It is generally not necessary to call ibcac(). It is provided for advanced users

who want direct, low-level access to the GPIB bus.

Return value

The value of ibsta is returned.

ibclr

Name

ibclr -- clear device (device)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibclr(int ud);

Description

ibclr() sends the clear command to the device specified by ud.

Return value

The value of ibsta is returned.

ibcmd

Name

ibcmd -- write command bytes (board)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibcmd(int ud, const void *commands, long num_bytes);

Description

ibcmd()

writes

the

command

bytes

contained

in

the

array

commands

to

the

bus.

The

number

of

bytes

written

from

the

array

is

specified

by

num_bytes.

The

ud

argument

is

a

board

descriptor,

and

the

board

must

be

controller-in-charge.

Most

of

the

possible

command

bytes

are

declared

as

constants in the header files. In particular, the constants GTL, SDC, PPConfig,

GET,

TCT,

LLO,

DCL,

PPU,

SPE,

SPD,

UNL,

UNT,and

PPD

are

available.

Additionally,

the

inline

functions

MTA(),

MLA(),

MSA(),

and

PPE_byte()

are

available for producing

'my

talk address',

'my

listen

address',

'my

secondary

address', and 'parallel poll enable' command bytes respectively.

It is generally not necessary to call ibcmd(). It is provided for advanced users

who want direct, low-level access to the GPIB bus.

Return value

The value of ibsta is returned.

ibcmda

Name

ibcmda -- write command bytes asynchronously (board)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibcmda(int ud, const void *commands, long num_bytes);

Description

ibcmda()

is

similar

to

ibcmd()

except

it

operates

asynchronously.

ibcmda()

does not wait for the sending of the command bytes to complete, but rather

returns immediately.

While an asynchronous operation is in progress, most library functions will fail

with

an

EOIP

error.

In

order

to

sucessfully

complete

an

asynchronous

operation, you must call ibwait() until the CMPL bit is set ibsta. Asynchronous

operations may also be aborted with an ibstop() or ibonl() call.

Return value

The value of ibsta is returned.

ibconfig

Name

ibconfig -- change configuration (board or device)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibconfig(int ud, int option, int setting);

Description

Changes

various

configuration

settings

associated

with

the

board

or

device

descriptor ud. The option argument specifies the particular setting you wish to

modify.

The

setting

argument

specifies

the

option's

new

configuration.

To

query the descriptor's configuration, see ibask().

Table 1. ibconfig options

option

IbcPAD

value

(hexadecimal)

0x1

effect

used

for

board/device

Sets

GPIB

board or device

primary

address.

Same as ibpad()

Sets

GPIB

board or device

secondary

address.

Same

as ibsad()

Sets timeout for io

board or device

operations.

Same

as ibmto().

If

setting

is

nonzero,

EOI

is

asserted

with

last

byte

on

writes.

IbcSAD

0x2

IbcTMO

0x3

IbcEOT

0x4

IbcPPC

0x5

IbcREADDR

0x6

IbcAUTOPOLL

0x7

IbcCICPROT

0x8

IbcSC

0xa

IbcSRE

0xb

IbcEOSrd

0xc

IbcEOSwrt

0xd

Same as ibeot().

Sets

parallel

poll

configuration.

Same as ibppc().

Useless,

included

for

compatibility

only.

If

setting

is

nonzero

then

automatic

serial

polling is enabled.

Useless,

included

for

compatibility

only.

If

setting

is

nonzero,

board

becomes

system

controller.

Same

as ibrsc().

If

setting

is

nonzero

then

board

asserts

REN

line.

Otherwise REN is

unasserted.

Same as ibsre().

If

setting

is

nonzero

then

reads

are

terminated

on

reception

of

the

end-of-string

character.

See

ibeos(),

in

particular

the

REOS bit.

If

setting

is

nonzero then EOI

is

asserted

whenever

the

end-of-string

character

is

sent.

See

ibeos(),

in

particular

the

board

device

board

board

board

board

board or device

board or device

IbcEOScmp

0xe

IbcEOSchar

0xf

IbcPP2

0x10

IbcTIMING

0x11

XEOS bit.

If

setting

is

board or device

nonzero then all 8

bits

are

used

to

match

the

end-of-string

character.

Otherwise

only

the

least

significant

7

bits

are

used.

See

ibeos(),

in

particular

the

BIN

bit.

Sets

the

board or device

end-of-string

byte. See ibeos().

If

setting

is

board

nonzero

then

the

board

is

put

into

local

parallel

poll

configure

mode,

and

will

not

change

its

parallel

poll

configuration

in

response

to

receiving

'parallel

poll

enable'

command

bytes

from

the

controller-in-char

ge. Otherwise the

board

is

put

in

remote

parallel

poll

configure

mode.

Some

older

hardware

does

not

support

local

parallel

poll

configure mode.

Sets the T1 delay.

board

Use

setting

of

1

for

2

IbcReadAdjust

0x13

IbcWriteAdjust

0x14

IbcEventQueue

0x15

microseconds,

2

for

500

nanoseconds,

or

3

for

350

nanoseconds.

These

values

are

declared

in

the

header

files

as

the

constants

T1_DELAY_2000

ns,

T1_DELAY_500n

s,

and

T1_DELAY_350n

s.

A

2

microsecond

T1

delay

is

safest,

but

will

limit

maximum transfer

speeds

to

a

few

hundred

kilobytes

per second.

If

setting

is

board or device

nonzero then byte

pairs

are

automatically

swapped

during

reads.

Presently,

this

feature

is

unimplemented.

If

setting

is

board or device

nonzero then byte

pairs

are

automatically

swapped

during

writes.

Presently,

this

feature

is

unimplemented.

If

setting

is

board

nonzero

then

the

event

queue

is

enabled.

The

event

queue

is

disabled

by

IbcSPollBit

0x16

IbcSendLLO

0x17

IbcSPollTime

0x18

IbcPPollTime

0x18

IbcEndBitIsNorm

al

0x1a

default.

If

the

setting

is

nonzero

then

the

use of the SPOLL

bit

in

ibsta

is

enabled.

If

the

setting

is

nonzero

then

devices

connected

to

this

board

are

automatically

put

into

local

lockout

mode

when

brought

online

with

ibfind()

or

ibdev().

Sets

timeout

for

serial

polls.

The

setting

must

be

between

0

and

17,

which

correspond to the

same

time

periods

as

in

ibtmo().

Sets

timeout

for

parallel polls. The

setting

must

be

between

0

and

17,

which

correspond to the

same

time

periods

as

in

ibtmo().

If

setting

is

nonzero

then

the

END bit of ibsta is

set

on

reception

of

the

end-of- string

character

or

EOI

(default).

Otherwise

END

board

board

device

board

board or device

IbcUnAddr

0x1b

IbcHSCableLengt

h

IbcIst

0x1f

0x20

IbcRsv

0x21

IbcBNA

0x200

bit

is

only

set

on

EOI.

If

setting

is

nonzero

then

UNT

(untalk)

and

UNL

(unlisten)

commands

are

automatically

sent

after

a

completed

io

operation

using

this

descriptor.

This

option

is

off

by default.

Useless,

included

only

for

compatibility.

Sets

the

individual

status

bit,

a.k.a.

'ist'.

Same as ibist().

Sets

the

current

status

byte

this

board

will

use

to

respond

to

serial

polls.

Same

as

ibrsv().

Changes

the

GPIB

interface

board

used

to

access

a

device.

The

setting

specifies

the

board index of the

new

access

board.

This

configuration

option is similar to

ibbna() except the

new

board

is

specified

by

its

board

index

instead

of

a

name.

device

board

board

board

device

Return value

The value of ibsta is returned.

ibeos

Name

ibeos -- set end-of-string mode (board or device)

Synopsis

class=FUNCSYNOPSISINFO

#include

int ibeos(int ud, int eosmode);

Description

ibeos()

is

used

to

set

the

end-of- string

character

and

mode.

The

least

significant

8

bits

of

eosmode

specify

the

eos

character.

You

may

also

bitwise- or one or more of the following bits to set the eos mode:

Table 1. End-of- String Mode Bits

constant

REOS

value (hexadecimal)

0x400

meaning

Enable

termination

of

reads

when

eos

character is received.

Assert

the

EOI

line

whenever

the

eos

character

is

sent

during

writes.

Match

eos

character

using

all

8

bits

(instead

of

only

looking

at

the

7

least significant bits).

XEOS

0x800

BIN

0x1000

Return value

The value of ibsta is returned.

ibeot

Name

ibeot -- assert EOI with last data byte (board or device)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibeot(int ud, int send_eoi);

Description

If send_eoi is non-zero, then the EOI line will be asserted with the last byte

sent by calls to ibwrt() and related functions.

Return value

The value of ibsta is returned.

ibevent

Name

ibevent -- get events from event queue (board)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibevent(int ud, short *event);

Description

ibevent() is used to obtain the oldest event stored in the event queue of the

board specified by the board descriptor ud. The EVENT bit of ibsta indicates

that

the

event

queue

contains

1

or

more

events.

An

event

may

be

a

clear

command, a trigger command, or reception of an interface clear. The type of

event is stored in the location specified by event and may be set to any of the

following values:

Table 1. events

constant

EventNone

EventDevTrg

value

0

1

description

The

board's

event

queue is empty

The

board

has

received

a trigger command from

the controller-in-charge.

The

board

has

received

a

clear

command

from

the controller-in-charge.

The

board

has

received

an

interface

clear

from

the

system

controller.

Note,

some

models

of

GPIB

interface

board

lack

the

ability

to

report

interface clear events.

EventDevClr

2

EventIFC

3

The

event

queue

is

disabled

by

default.

It

may

be

enabled

by

a

call

to

ibconfig().

Each

interface

board

has

a

single

event

queue

which

is

shared

across all processes and threads. So, only one process can retrieve any given

event from the queue. Also, the queue is of finite size so events may be lost

(ibevent() will return an error) if it is neglected too long.

Return value

The value of ibsta is returned.

ibfind

Name

ibfind -- open a board or device (board or device)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibfind(const char *name);

Description

ibfind() returns a board or device descriptor based on the information found in

the

configuration

file.

It

is

not

required

to

use

this

function,

since

device

descriptors can be obtained with ibdev() and the 'board index' (minor number

in the configuration file) can be used directly as a board descriptor.

Return value

If sucessful, returns a (non-negative) board or device descriptor. On failure, -1

is returned.

ibist

Name

ibist -- set individual status bit (board)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibist(int ud, int ist);

Description

If

ist

is

nonzero,

then

the

individual

status

bit

of

the

board

specified

by

the

board descriptor ud is set. If ist is zero then the individual status bit is cleared.

The individual status bit is sent by the board in response to parallel polls.

On success, iberr is set to the previous ist value.

Return value

The value of ibsta is returned.

ibln

Name

ibln -- check if listener is present (board or device)

Synopsis

class=FUNCSYNOPSISINFO#include

int ibln(int ud, int pad, int sad, short *found_listener);

Description

ibln()

checks

for

the

presence

of

a

device,

by

attempting

to

address

it

as

a

listener. ud specifies the GPIB interface board which should check for listeners.

If ud is a device descriptor, then the device's access board is used.

The GPIB address to check is specified by the pad and sad arguments. pad

specifies

the

primary

address,

0

through

30

are

valid

values.

sad

gives

the

secondary address, and may be a value from 0x60 through 0x7e (96 through

126), or one of the constants NO_SAD or ALL_SAD. NO_SAD indicates that

no

secondary

addressing

is

to

be

used,

and

ALL_SAD

indicates

that

all

secondary addresses should be checked.

If the board finds a listener at the specified GPIB address(es), then the variable

specified by the pointer found_listener is set to a nonzero value. If no listener is

found, the variable is set to zero.

The board must be controller-in-charge to perform this function. Also, it must

have the capability to monitor the NDAC bus line (see iblines()).

Return value

The value of ibsta is returned.

iblines

Name

iblines -- monitor bus lines (board)

Synopsis

class=FUNCSYNOPSISINFO#include

int iblines(int ud, short *line_status);

Description

iblines() is used to obtain the status of the control and handshaking bus lines of

the bus. The board used to monitor the bus is specified by the ud argument,

and the status of the various bus lines are written to the location specified by

line_status.

Some older chips are not capable of reporting the status of the bus lines, so

each

line

has

two

corresponding

bits

in

line_status.

One

bit

indicates

if

the

board

can

monitor

the

line,

and

the

other

bit

indicates

the

line's

state.

The

meaning of the line_status bits are as follows:

Table 1. line status bits

constant

ValidDAV

ValidNDAC

ValidNRFD

ValidIFC

ValidREN

ValidSRQ

ValidATN

ValidEOI

BusDAV

value

0x1

0x2

0x4

0x8

0x10

0x20

0x40

0x80

0x100

description

The BusDAV bit is valid.

The

BusNDAC

bit

is

valid.

The

BusNRFD

bit

is

valid.

The BusIFC bit is valid.

The BusREN bit is valid.

The BusSRQ bit is valid.

The BusATN bit is valid.

The BusEOI bit is valid.

Set/cleared

if

the

DAV

line

is

asserted/unasserted.

Set/cleared if the NDAC

line

is

asserted/unasserted.

Set/cleared

if

the

NRFD

line

is

asserted/unasserted.

Set/cleared

if

the

IFC

line

is

asserted/unasserted.

BusNDAC

0x200

BusNRFD

0x400

BusIFC

0x800