serial comm problem

[win_832001]

hello there..i was trying to control the relay 12V by using the serial port comm.the PIC that i used is PIC 16 F84. can someone check my VB PIC basic code below,it does not work:

VB code :
Private Sub Form_Load()
Optstate(0).Value = True
MSComm1.CommPort = 1
MSComm1.Settings = "2400,n,8,1"
MSComm1.DTREnable = False
MSComm1.RThreshold = 1
MSComm1.InputLen = 1
MSComm1.PortOpen = True
End Sub
Private Sub Command1_Click()
Dim pinstate As Long
If Optstate(0).Value = True Then
pinstate = 0
Else
pinstate = 1
End If
MSComm1.Output = Chr$(255) & Chr$(pinstate)
End Sub

Private Sub form_unload(cancel As Integer)
MSComm1.PortOpen = False

End Sub


PIC code :
INCLUDE "modedefs.bas"

Si VAR PORTA.4
RELAY VAR PORTB.2
pinstate VAR BYTE

main

SerIn Si,4,["255"],pinstate

IF pinstate=1 Then
GoSub Relayon
Else
GoSub Relayoff
EndIF

Relayon:
High RELAY
Return

Relayoff:
Low RELAY
Return

[Bruce]

Place a goto Main at the end, and change ["255"] to [255].

Main:
    SerIn Si,4,[255],pinstate
    IF pinstate=1 Then 
      GoSub Relayon
    Else 
      GoSub Relayoff
    EndIF
    GOTO Main ' <-- forgot this

Relayon:
    High RELAY
    Return

Relayoff:
    Low RELAY 
    Return

[win_832001]

tq for the reply..actually there are problem appear after i tried the code u have given..when i'm sending '0' from VB and after that send "1" to th PIC.the relay does not "on".

the problem also appear after once i "on" and "off" the relay, and then i want to "on" again the relay is not "on"

[mister_e]

how do you interface your PIC to the PC? resistor i guess, wich value? 1k-10K is fair enough. geater than 10K seems to cause erratic behavior in some case.

Could also be a hardware problem as we see often.. psu filtering or else.

[win_832001]

the resistor i used is is 22K..

[schu4647]

The PIC may not supply enough current to trigger your relay. Put an LED in its place and make sure it is going on and off.