Help on RS422

RichardF

I am·trying to learn·RS422 comms using two BS2SX-IC's connected by two LTC 490's. The following·are my super simple master and slave programs, which won't work!! Can anyone see why not?

' {$STAMP BS2sx}
' {$PBASIC 2.5}
'Master send RS422
TX PIN 12
RX PIN 13
HIGH TX
DO
· LOOP UNTIL RX = 1
PAUSE 1
SEROUT TX,18447,[noparse][[/noparse]"X"]
END

' {$STAMP BS2sx}
' {$PBASIC 2.5}
'Slave RS422
TX PIN 12
RX PIN 13
msgIn VAR Byte
DO
· LOOP UNTIL RX = 1
HIGH TX
SERIN RX,18447,[noparse][[/noparse]msgIn]
LOW TX
DEBUG msgIn
END

Thanks for the help,Richard

marzec309

If you have two serial ports you can hook up both stamps. And debug both at the same time it might help but try this code its not tested though.

Try this

' {$STAMP BS2sx}
' {$PBASIC 2.5}
'Master send RS422
TX PIN 12
RX PIN 13
Main:
  HIGH TX
  DO
    LOOP UNTIL RX = 1
    LOW TX
  PAUSE 10                       'changed from 1 to 10
  SEROUT TX,18447,[noparse][[/noparse]"X"]
  DEBUG "Sent"
  GOTO Main

END

' {$STAMP BS2sx}
' {$PBASIC 2.5}
'Slave RS422
TX PIN 12
RX PIN 13
msgIn VAR Byte
Main:
  DO
    LOOP UNTIL RX = 1
  HIGH TX
  PAUSE 15
  SERIN RX,18447,500,TimeOut,[noparse][[/noparse]msgIn]     'Wait for 1/2 sec for serial to start if it doesn't goto TimeOut
  LOW TX
  DEBUG ? msgIn
END

TimeOut:
  DEBUG "Serial Timed Out",CR,
        "Restarting",CR
  GOTO Main
END

PJAllen

First things first.·
In neither of your listed programs have you any commands to execute·between the DO and the following LOOP,

' {$STAMP BS2sx}
' {$PBASIC 2.5}
'Master send RS422
TX PIN 12
RX PIN 13
HIGH TX
[color=red]DO
  LOOP UNTIL RX = 1[/color]
PAUSE 1
SEROUT TX,18447,[noparse][[/noparse]"X"]
END

so it'll just dither that way until RX=1, where it'll serout once and END.· Marzec did it, too.· So, what gives?

The first should be:

' {$STAMP BS2sx}
' {$PBASIC 2.5}

'Master send RS422

TX PIN 12
RX PIN 13

HIGH TX

DO
 SEROUT TX,18447,[noparse][[/noparse]"X"]
 PAUSE 10

LOOP UNTIL RX = 1

END

There's unfinished business, still.· You have RX Pin 13, but is it an input or an output?· [noparse][[/noparse]SEROUT takes care of TX, forcing it to be·an output.]

marzec309

·

PJ Allen said...
First things first.·
In neither of your listed programs have you any commands to execute·between the DO and the following LOOP,

' {$STAMP BS2sx}
' {$PBASIC 2.5}
'Master send RS422
TX PIN 12
RX PIN 13
HIGH TX
[color=red]DO
  LOOP UNTIL RX = 1[/color]
PAUSE 1
SEROUT TX,18447,[noparse][[/noparse]"X"]
END

so it'll just dither that way until RX=1, where it'll serout once and END.· Marzec did it, too.· So, what gives?

The first should be:

' {$STAMP BS2sx}
' {$PBASIC 2.5}

'Master send RS422

TX PIN 12
RX PIN 13

HIGH TX

DO
 SEROUT TX,18447,[noparse][[/noparse]"X"]
 PAUSE 10

LOOP UNTIL RX = 1

END

There's unfinished business, still.· You have RX Pin 13, but is it an input or an output?· [noparse][[/noparse]SEROUT takes care of TX, forcing it to be·an output.]

The reson I repeated that part of his program is because I believed he was using it as a program hold, and didn't want to completely rewrite his program. Basicaly wait for the other stamp to be ready then progress when it is.