[TriEmbed] ADC

Scott Hall scottghall1 at gmail.com
Tue Oct 27 14:38:07 CDT 2020


Modbus can be used over a TTL serial link -- as long as you take electrical
characteristics into consideration.  In fact, modbus has been used in many
connection types, even parallel buses and wireless links.  I've even seen modbus
embedded in another protocol layer, such as Zigbee, MQTT or of course TCP.  A
RS485 link requires a balancing circuit or transformers at either end and is
really designed for long or multidevice signaling, and not needed for short wire
or direct bus connections in close proximity.

- sgh

On 10/26/20 10:23 AM, Rodney Radford via TriEmbed wrote:
> I have not used the modbus Arduino code before, but it does look interesting.
> However in reading the description they state it is designed to use with
> either their Ethernet shield or the RS485 shield, but I did not see anything
> on running it with just a standalone Arduino. If it is possible to just use
> the TTL serial port of the Arduino, that would be very nice, indeed.
>
> On Mon, Oct 26, 2020 at 8:20 AM John Vaughters via TriEmbed
> <triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
>
>     >You might avoid the ADC chip and instead use an Arduino.
>
>     +1
>
>     My favorite combo is to use the Rpi UART with a nano arduino that has 8
>     ADCs @ 10bit and you can get them for like $5. I like to make the ardiuno
>     dumb with a modbus slave. The combination with the UART/MODBUS is
>     extremely reliable. You can also pump it out to tcp with the mbusd utility.
>
>     Just some thoughts
>
>     John Vaughters
>
>     On Monday, October 26, 2020, 7:14:39 AM EDT, John Moore via TriEmbed
>     <triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
>>     You might avoid the ADC chip and instead use an Arduino.  Some Arduino's
>>     give an 8 channel ADC at 10 bits resolution. 
>>      https://www.arduino.cc/en/Tutorial/Foundations/AnalogInputPins
>>      
>>     -John Moore
>>
>>     On Sun, Oct 25, 2020 at 10:34 AM The MacDougals via TriEmbed
>>     <triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
>>>     I  am looking for an 8 channel ADC chip.
>>>     10 bit is sufficient.  I2C is preferred but SPI would be OK.
>>>     Hand solderable package highly preferred.
>>>     I found these:
>>>     https://www.ti.com/lit/ds/symlink/adc128d818.pdf  - $5.30 at DigiKey
>>>     https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf
>>>     - $7.34 at Digikey
>>>
>>>     Any opinions? Anyone have something in their personal stock?
>>>     Anyone interested in sharing shipping costs on a DigiKey order?
>>>
>>>     ---> Paul
>

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