RF Transmitters/Receivers

bald Eagle

I purchased 2 transmitters and 1 receiver to make a simple remote system (push button, machine turns on). No problem with 1 transmitter 1 receiver, worked fine on bench. When I introduced the 2 transmitter, I found out I had a problem. I suppose 2 transmitters can't pulse and ser at the same time. Can I get some ideas on how to solve my issue?

Mike Green

Two transmitters will interfere with each other. Solutions to your issue depend on what you want to do. If you want the possibility of both transmitters being on at the same time, you will need 2 receivers and each transmitter / receiver pair will need to be on a different frequency. You do need to describe what kind of behavior you want with these including for the case where both transmitters are used at the same time.

bald Eagle

Recvr has input and turns on a opto that turns on a motor. The 2 transmitters are at separate locations to remotely turn on same motor. So far one xmtr works fine. Can it be corrected with program instruction?

Mike Green

You haven't given any information about the transmitters and receiver, but I assume they're on the same frequency. They'll interfere with each other if the "button" on both is pushed at the same time. The only way you can deal with that is to either not turn them both on at the same time or have two different frequencies (and two receivers as I mentioned).

There are other solutions, but they're more complex and you couldn't do it with what you currently have.

bald Eagle

Okay, Xmtr's and Rvr 433.92MHz. Purchased from Parallax. Application is RF push button to start a PLC Controlled Vacuum Sys. Just needed one input to PLC from the Rvr output. The Xmtr's are in two locations with one input (a push button) so that either location can start unit with an output.·Used the sample·program that came with·stamp modules and modified it to a·very simple·'if·input is 1 (push button)·make output 1 else stay 0'.

Silly me, thought that both xmtr's could have the same logic and the rcvr would listen to either one of them. One xmtr and rcvr set work great. As soon as I apply power to second xmtr, that's when things get real iffy on who the rcvr is going to listen to.

My question is; is there a way to program this to use 2 xmtr's and 1 rcvr?

I am embarrassed on the program, but, here it is.

' TxCode_v_1.0.bs1
'{$STAMP BS1}
'{$PBASIC 1.0}
'
'Parallax 433.92 MHz RF Transmitter (#27980) Sample Tx Code (BS1)
'Connect I/O Pin 1 of the BS1 to the DATA line on the RF module
'Connect +5v (Vdd) to the 5v line, connect Ground (Vss) to the GND line
'Note the PULSOUT instruction: this helps the receiver sync with
'the transmitter, especially after lapses in communication.
'This code transmits at 2400 baud

SYMBOL x =PIN5
SYMBOL y = PIN4

DIRS = %00100000

Start:

PULSOUT 0, 300 'Sync pulse for the receiver

x = 1

SEROUT 0, N2400, ("HEY", PIN5)
'SEROUT 0, N2400, ("YOU", PIN5)

IF y = 0 THEN start2

GOTO start

Start2:

PULSOUT 0, 300 'Sync pulse for the receiver

x = 0

SEROUT 0, N2400, ("HEY", PIN5)
'SEROUT 0, N2400, ("YOU", PIN5)

IF y = 1 THEN start

GOTO start2

+++++++++++++++++++++++++++++++++++

'RxCode_v_1.0.bs1
'{$STAMP BS1}
'{$PBASIC 1.0}

SYMBOL x = PIN5
SYMBOL y = PIN4
OUTPUT 5
INPUT 4
Start:
· SERIN 0, N2400, ("HEY"), PIN5
· 'SERIN 0, N2400, ("YOU"), PIN5
GOTO Start

Mike Green

I will say once more again ... This has nothing to do with the logic involved or the program involved. It's strictly due to the two transmitters' signals interfering with each other when they're both on.

SALTYDOGGS

set the transmitters up so they only have power and transmit a "1" when the button is pressed.· It sounds like the problem you have is one is transmitting "1" the other "0", and the loudest one wins..