Picaxe 40x2 chip.
What is the maximum cable length, that would still give a reliable signal at 9600baud?
using shielded twisted pairs.
It is the same project, just thinking of alternatives.Is this the same application as you were considering ERF transceivers for? - the outdoor large scale model railway? If so, perhaps one should steer you straight away towards RS485 rather than the less noise-resistance and less-transmission range of the RS232. Hippy asks if you are actually using RS232 or are you proposing the serial output of a PICAXE? RS232 requires drivers and is usually operated at +/-12 volts against the PICAXE 0 to +5 volts. If you are thinking of long-distance outdoor cabling and want reliable operation in an environment that is in any way electrically noisy (I presume your locomotives are electric?) then start off by looking at RS485 drivers. Think of RS485 being like the ARF modules, RS232 being XRF modules and PICAXE serial being ERF modules and you may get my drift.
Do your really need 9600 baud? Perhaps if you could let us know precisely what type of control signals you are trying to transmit and for what purpose we could be of more help. (If you can slow down your data-rate then you can achieve much longer range; that applies generally to radio transmission as well as cable-linking).
No Picaxe chip can transmit RS232 without other circuitry, though. RS232 specifies signal levels of + and - 12V, not 0V and 5V, as a part of the protocol, hence the need to use a driver chip like the Max232 or similar. Those chips have the circuitry to boost Picaxe serial data to RS232 that then allows pretty long cable lengths.It is the same project, just thinking of alternatives.
I was originally asking for max length of rs232 from picaxe, without adding other circuitry.
Live steam! - Wonderful!not electric locos, live steam.
Perhaps not the best idea; extension cables tend to attenuate signal transmission to antennae; there is always some signal loss in an extension cable. Better to keep the quarter wave directly on the ERF and extend the power cable and serial cables from the base unit to the ERF, within a reasonable distance of course.It is the same project, just thinking of alternatives.
other thought is to use a 'reverse sma extension cable' for the aerial instead.
RS232 from PICAXE; Jeremy Harris has reiterated my comment in the previous post with some further clarity. Again, RS232 uses +12 volts as its "high" state and NEGATIVE 12 volts for its "low state"; if you like, there is a 24 volt swing around zero as the pulses are transmitted. It is this swing from positive to negative that ensures the effective transmission over a distance; but still not a great distance. You seem not to catch on to this difference between RS232 and PICAXE serial out which Jeremy highlights is NOT RS232 and you cannot use the RS232 cabling references that have used for your subsequent cable-length calculations when considering a 0-5 volt PICAXE serial.I was originally asking for max length of rs232 from picaxe, without adding other circuitry.
To keep it simple, as I understand,
15M of standard cable (2500pf) gives me 15M at 9600baud rate.
utp cat5 cable gives longer range.
Because the CISECO ARF transceiver has a receive signal amplifier as well as a booster on the transmit side, if you can use the ARF as the 'master' unit you may achieve the range that you need. ARF's talk to XRFs or ERFs at a much greater distance than XRF-to-XRF can. This may just work for you.I now have an ARF ciesco module, to use as a master. it's 3.3v so will need make a pcb to add a 3.3 voltage regulator and a 'level logic shifter', not a great problem.
thanks for info Besqueut,