Hi,
I am currently trying to devise a communication loop between a Picaxe master and x amount of MCU slaves (tested with 6 so far). The master sends data to each slave in turn and the slave will return data back. I have 2 wires for the serial in/out and 2 for the 24v power supply to power the slaves/other peripherals (audio modules). Tried putting it together quickly and I am able to flash an LED on each slave with no issue.
Is there any way of modulating the serial in and out onto the +ve -ve so that I have power and data on these two wires instead of 4? I haven't got that great knowledge of electronics- I am able to assemble circuits provided I have a schematic to follow but I like a challenge and I want to do this with 2 wires only. I have looked into Foundation Fieldbus and Meterbus but it seems too "industrial" and complicated for someone like me. Has anyone got any reliable ideas/examples of where this has been done?
I already know it isn't as simple as "adding" a voltage onto the source when the serial signal is high because of resistances in cables/Vregulators causing voltage drops. I also assume it'll be harder if I used a DAC to output an analog wave on the 24v power supply due to interference. I have no real clue on how to attempt this
Data speed: as fast but reliable as possible. All the Picaxe slaves use Hserin. If the slave misses the command the master will keep sending it for x tries and then display a fault on the control panel screen.
The commands I will send to the slaves are my own custom protocol.
Example:
Master -> Slave 3
P003R (P=poll, 003=slave address, R=return an acknowledgement).
Slave 3-> Master
R003NNN010 (R=return ack, 003=address,N=no smoke,N=no heat,N=no internal fault,0=sounder off, 1=speech mode enabled,0=Strobe off).
I am currently trying to devise a communication loop between a Picaxe master and x amount of MCU slaves (tested with 6 so far). The master sends data to each slave in turn and the slave will return data back. I have 2 wires for the serial in/out and 2 for the 24v power supply to power the slaves/other peripherals (audio modules). Tried putting it together quickly and I am able to flash an LED on each slave with no issue.
Is there any way of modulating the serial in and out onto the +ve -ve so that I have power and data on these two wires instead of 4? I haven't got that great knowledge of electronics- I am able to assemble circuits provided I have a schematic to follow but I like a challenge and I want to do this with 2 wires only. I have looked into Foundation Fieldbus and Meterbus but it seems too "industrial" and complicated for someone like me. Has anyone got any reliable ideas/examples of where this has been done?
I already know it isn't as simple as "adding" a voltage onto the source when the serial signal is high because of resistances in cables/Vregulators causing voltage drops. I also assume it'll be harder if I used a DAC to output an analog wave on the 24v power supply due to interference. I have no real clue on how to attempt this
Data speed: as fast but reliable as possible. All the Picaxe slaves use Hserin. If the slave misses the command the master will keep sending it for x tries and then display a fault on the control panel screen.
The commands I will send to the slaves are my own custom protocol.
Example:
Master -> Slave 3
P003R (P=poll, 003=slave address, R=return an acknowledgement).
Slave 3-> Master
R003NNN010 (R=return ack, 003=address,N=no smoke,N=no heat,N=no internal fault,0=sounder off, 1=speech mode enabled,0=Strobe off).
