Measurement-computing Personal488 rev.3.0 For DOS & Windows 3.Xi Instrukcja Użytkownika Pobierz pdf (Strona 117)

8K. Other Languages II. SOFTWARE GUIDES - 8. Driver488/DRV

II-102 Personal488 User’s Manual, Rev. 3.0

•

: A response of

indicates that Driver488/DRV is ready to receive a command. It has no data to

read, nor is it expecting data for output to the IEEE 488 bus. Driver488/DRV is forced into this

state by the

IOCTL BREAK

command.

•

: A response of

indicates that Driver488/DRV has a response ready to be read by the user’s

program. The program must read the response before sending a new command (except

IOCTL BREAK

) or a

SEQUENCE - DATA HAS NOT BEEN READ

error occurs.

•

: A response of

indicates that Driver488/DRV is waiting for data to

OUTPUT

to the IEEE 488

bus. The user’s program must send the appropriate data with terminators as needed to

Driver488/DRV. Attempting to read from Driver488/DRV while it is waiting for data causes a

SEQUENCE - NO DATA AVAILABLE

error.

•

: A response of

indicates that Driver488/DRV is waiting for the completion of a command.

This is similar to a response of

except that Driver488/DRV is waiting for a command, rather than

for data to

OUTPUT

The

IOCTL Read

response can be read from Driver488/DRV as:

ioctlbufDB 0 ;IOCTL Read response buffer

ioctllenEQU $-ioctllen ;Length of buffer

mov AX,4402h ;IOCTL Read

mov BX,ieee ;File handle

mov CX,ioctllen ;# chars to read

mov DX,offset

ioctlbuf

;DS:DX - buffer

int 21h ;Execute DOS function

jc error ;Check for error

Data & Command Communication

Once Driver488/DRV has been opened, configured for

RawMode

communication, and reset with the

IOCTL Write

command

BREAK

, we are ready to communicate with Driver488/DRV and control the

IEEE 488 bus. The BASIC commands:

PRINT#1,"HELLO"

LINE INPUT#1,A$

might be implemented in assembly language as:

cr EQU 0Dh ;Carriage-return

lf EQU 0Ah ;Line-feed

hello DB “HELLO”,,cr,,lf ;HELLO command with terminators

hellolen EQU $-hello ;HELLO command length

response DB 256 DUP (?) ;Place to put Driver488/DRV response

responselen EQ $-response ;Length of response buffer

recvdlen DW ? ;Place to keep # chars in response

mov AH, 40h ;DOS Write function

mov BX, ieee ;File handle

mov CX, hellolen ;Command length

mov DX, offset hello ;DS:DX - command

int 21h ;Execute DOS function

jc error ;Check for error

mov AH, 3Fh ;DOS Read function

mov BX, ieee ;File handle

mov CX, responselen ;Buffer length

mov DX, offset

response

;DS:DX - buffer

int 21h ;Execute DOS function

jc error ;Check for error

mov recvdlen, AX ;Save # of characters received

In this way, data and commands can be transferred to or from Driver488/DRV.

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