Arduino Ethernet Shield Multiple Connections and the power usage issue

Using Arduino Project Guidance
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:o

I have a project where the ESP32 would be perfectly suitable however... there are some issues which makes me fall back to the good old Arduino.

I would need in a project which can measure voltage and current (ACS 712) from a load then make that data available over telnet. As my research shows the available current sensors for ESPs on the market can do around 3.6A max, I need more and then I would like to control relays, which again available from 3.3V versions but for double of the cost of the regular 5V relays and ultimately I already built circuit with 5V arduino to do all these but with the ESP32 I would have to throw out all my work and start it from stratch so one word than a hundred, I give up with using the ESP32.

I need the data to be provided through telnet to multiple computers on the network. For this I could just connect the arduino to a raspberry pi through USB but low power consumption is a key point of this project and I don't want to use a full computer.

I was considering to use the: Ethernet Shield W5100

The latest Arduino Ethernet Shield on the market. As my research shows the power consumption of this board is quite a lot, 150mA so coupled with a Leonardo = 200mA constant current draw.

I wouldn't mind using wifi board but there isn't? any official yet. All I could find are ESP shields such as:

https://www.ebay.com/itm/ESP8266-Serial-Port-WiFi-Expansion-Board-UNO-R3-Board-Shield-ESP-13-for-Arduino/172060795021?hash=item280f9f608d:rk:1:pf:0

WiFi current: continuous transmission: ?70mA (200mA MAX) + 50mA leonardo so we are still a bit better than using the Ethernet shield.

Could you recommend any other TCP/IP based (wired or wireless) lower power communication solution?

For those who have experience with the ethernet shield and wifi shields I would particularly like to know if multiple simoulteanous TCP connections are possible or NOT possible for them:

I would not have that many clients just 5-10 but they can connect any time to the Arduino to poll the data through telnet and they cannot be blocked by each other.

If I would be using a standard Raspberry PI with C code this would not be an issue, that would even handle hundreds of clients with socket server.

My other big concern here is exhaustion, I want this project to work roboustly through a long time, not that it runs out of handles, sockets or it just crashes at a point.

All suggestions are welcome!

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For those who have experience with the ethernet shield and wifi shields I would particularly like to know if multiple simoulteanous TCP connections are possible or NOT possible for them:

The WizNet5100 can handle up to 4 simultaneous socket connections.

would not have that many clients just 5-10

You should consider using a in-between service to handle all clients.

The latest Arduino Ethernet Shield on the market. As my research shows the power consumption of this board is quite a lot, 150mA so coupled with a Leonardo = 200mA constant current draw.

Low power consumption is usually not a priority with cable bound applications. Please specify why power consumption is a problem in your case.

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EthernetServer can handle only one client at time. The client must disconnect or be stopped before next client can connect

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EthernetServer can handle only one client at time. The client must disconnect or be stopped before next client can connect

This is not true. It handles up to MAX_SOCK_NUM connections which can be open simultaneously. But in the end every single core processor can only handle one client at any given time. But it can have up to 4 connections open for the WizNet5100.

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pylon:
This is not true. It handles up to MAX_SOCK_NUM connections which can be open simultaneously. But in the end every single core processor can only handle one client at any given time. But it can have up to 4 connections open for the WizNet5100.

how handle second telnet client connecting to EthernetServer on port 23?

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Juraj:
how handle second telnet client connecting to EthernetServer on port 23?

sor

Juraj:
how handle second telnet client connecting to EthernetServer on port 23?

sorry, I remembered that the new version of Ethernet library has accept() method, which allows handling multiple clients