How to hang on RS485 additional features?

Good afternoon. There is a need to get a universal interface that will be used as a RS485, ADC, and discrete output. For RS485 you plan to use public MAX485 chip type etc. How realistic is it to hang on outputs and RS485 transistor keys, etc. to get the output and the ADC, saving at least half of the declared characteristics RS485? Maybe someone has experience of such perversions. It is planned in the software switch, no jumpers, etc., during configuration of the device. The question is very vague, but TK is there to draw not hunting, will answer any questions during the discussion. Thanks in advance.
June 7th 19 at 14:33
3 answers
June 7th 19 at 14:35
RS485 is not a bus where you can connect different devices, the connection between the two devices.
You need to hang the device on any controller, and it has to implement the functions you need, which you control via RS485. Or stretch several RS485 lines and connect individual devices.
I understand. The problem I have is that on my device on two pins you need to implement what is usually implemented on 6 pins, namely, RS485, ADC, and output 0-12V. In other words, I connect something via the RS485 bus in the Configurator press the button RS485 and everything works. Next, I unplug the twisted pair cable from the connector, the same connector connect the ribbon cable, the resistance of which, I need to measure it in Configurator click the button ADC and get the value, well and for example led similarly. How it works I understand how to combine about the same, there is only doubt whether the connection of additional lines for the extra resistances and capacitances, which lead RS485 in complete disrepair. Even more simply - on the same two pins, depending on the specific situation, you must be able to connect the light bulb, a rheostat or counter(RS485). To set once the mode and forgot to switch modes in the process of operation of the device is not provided. Sorry for the confusion, the device is just out of the discharge, so that all at once and cheaper... - Lowell.Kiehn commented on June 7th 19 at 14:38
this connection between the two devices

Of course not. This is the bus to which you can connect up to 255 devices (physically load capacity depends on the driver and may be limited). But even in the minimum version up to 32 devices may be connected.

TS: All of these inventions eventually lead to big operational problems, etc. Use standard solutions. - Stuart55 commented on June 7th 19 at 14:41
Yes , I was wrong - RS422 and RS232 is point to point, and do RS485 bus. - Guiseppe commented on June 7th 19 at 14:44
June 7th 19 at 14:37
how to reinvent the wheel with heteropoly transmission ??
to cram all STE in two pins can be elementary, in the simplest version of taking a set of analog keys.
for example, 2 sets of switch one-to-three sootvestvuyuschim with a switchable range of operating voltages and currents.
but the enquiry suffers from the utter inaccuracy, so I won't write. and psychics not.
option 2: pin chtoli mind. inept bicycles when operating out in one place.
It turns out the bike is not cool. Pins is not a pity, on the PCB these connectors as much as 16 pieces, but there are places where all 16 should be used as the RS485 transceivers(most of the attachments does not support mnogohodovki system, has its own "protocols" and are connected on a single bus), and where there all are connected as the ADC, variations of connections is practically unlimited, and the city under each individual device is impractical. If formulated a bit clearer, you need the following:
1) determination of the resistance circuit(voltage drop on it) resistance 0 - 10kω.
2) Selectable output 0-12V with a maximum current up to 3A.
3) the RS485 Transceiver, which will be able to work steadily on cable length 0-200m at a speed of 100-200кбит/s one device in the network.

I roughly understand how to make it work if you pull the line interface to the earth, nutrition, etc., the only question is, will not be broken if the health of the RS485 at the same time. - Lowell.Kiehn commented on June 7th 19 at 14:40
June 7th 19 at 14:39
Reluse to hang (as a variant of small solid optorele), which is inside of your device will commutate the signal at the receiver 485го, ADC to test pattern or a couple of keys implementing a 0-12V digital outputs. Is a kind of multiplexer. :)

To save the properties 485го to cut off all other devices as close as possible to the connector that would not have hung tails, going nowhere.
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