Specifications

Multi Slave Product Re£erence Manual
Section 2
MASTER PROCESSOR (RECEIVING MESSAGE FROM SLAVE)
IN
BIT
RET
OUT
WAIT1:
IN
BIT
JR
BIT
JR
IN
RET
A, (SLVSTAT)
SLVMSG,A
NZ
(MSGRST),A
A, (SLVSTAT)
SLVWRT,A
NZ,WAITl
SLVHLD,A
NZ,WAITl
A, (SLVDATA)
; GET SLAVE STATUS
; IS SLAVE MESSAGE BIT SET?
; NO, RESUME OTHER TASKS (ACTIVE LOW)
OUTPUT CLEARS SLAVE MESSAGE BIT
; (CONTENTS OF A-REG INSIGNIFICANT)
GET SLAVE STATUS BITS
IS SLAVE WRITING TO 5-100 PORT?
LOOP IF NOT
; IS SLAVE IN A HOLD CONDITION?
LOOP
IF NOT
; ALL IS READY - GET THE DATA BYTE
; AND RETURN TO CA~LING TASK
MASTER PROCESSOR (SENDING MESSAGE TO SLAVE>
LD
OUT
WAIT2:
IN
BIT
JR
WAIT3:
IN
BIT
JR
BIT
JR
LD
OUT
RET
A,OOOOOOlOB
(SLVSTAT),A
A, (SLVSTAT)
MASTER,A
NZ,WAIT2
A, (SLVSTAT)
SLVWRT,A
Z,WAIT3
SLVHLD,A
NZ,WAIT3
A,(HL)
(SLVDATA),A
SET MASTER MESSAGE BIT ...
••. SO THE SLAVE WILL SEE IT
GET SLAVE STATUS
HAS THE SLAVE RESET IT YET?
LOOP UNTIL HE HAS DONE SO
GET SLAVE STATUS AGAIN
IS SLAVE READING THE 5-100 PORT?
LOOP
IF NOT
IS SLAVE IN A HOLD CONDITION?
; LOOP IF NOT
GET BYTE TO SEND
SEND
IT TO THE SLAVE
AND RETURN TO CALLING TASK
SLAVE PROCESSOR (RECEIVING MESSAGE FROM MASTER)
IN
IN
RET
A,
(HASTER)
A, (DATAPORT)
; CLEAR MASTER MESSAGE BIT
AND IMMEDIATELY READ THE S-100 PORT
; RETURN TO CALLING TASK
SLAVE PROCESSOR (SENDING MESSAGE TO MASTER)
IN A, (SLVMSG)
LD A,B
OUT (DATAPORT),A
RET
;
SET SLAVE MESSAGE BIT
B-REG HAS DATA BYTE TO SEND
; OUTPUT DATA BYTE TO 5-100 DATA PORT
; RETURN TO CALLING TASK
Note that these examples transmit and receive only a single byte
at a ti~e and provide only a skeletal communications protocol.
The slave may utilize the 280 block input and output instructiona
to receive and trana~it any number o£ bytes to the master, though
the user should employ a slightly more sophisticated protocol
when doing so. In typical networking environments, the £iret
byte transmitted contains the length o£ the message to £ollow,
Implementation of such networking schemes i8 leit to the user.
MASTER/SLAVE COMMUNICATIONS
Page 2-7