Author Topic: I2C outputs on Nano-10  (Read 2351 times)

emulder

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I2C outputs on Nano-10
« on: August 12, 2020, 09:17:46 AM »
The Nano-10 has a 2x5 pin connector with I2C on it. Does anybody have a pinout for this connector?
I tried using I2C_WRITE &H60,5,2 and I2C_STOP in a 0.5 second loop, but I do not see activity on any of the pins on the connector.

Thanks, Edward

support

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Re: I2C outputs on Nano-10
« Reply #1 on: August 13, 2020, 07:04:29 AM »
The I2C port is normally disabled without the I2C-FRTC module. When you install the I2C-FRTC module you will be able to use the I2C commands to interface to other I2C devices.
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IdellSeitz

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Re: I2C outputs on Nano-10
« Reply #2 on: September 03, 2020, 09:50:19 AM »
Hello...i have little to ask here. What distance do you expect to send the I2C? Total length of all wires on the I2C bus? I2C is not very good with more than a few centimeters of wire. You have to work hard to get it up to the metres range. I have found SPI to be better over medium distance, like 2-3m, even though its specifications initially seem more limited.

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« Last Edit: September 04, 2020, 02:06:33 PM by IdellSeitz »

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Re: I2C outputs on Nano-10
« Reply #3 on: September 03, 2020, 12:37:12 PM »
You are right that I2C bus is usually meant for short distance (typically on board or on an adjacent board due to the fact that it only has active low output while high level output depends on pull up resistors. It should work over 20 to 30cm away but make sure that there is no noisy signal that can be coupled onto the I2C signal path.

The I2C-FRTC module that are sold with our FMD and Nano-10 PLCs however employs an I2C buffer chip which allows it to interface to other I2C buffer chip using higher voltage (up to 15VDC) and load capacitance of 4000pF. That can help to extend the I2C range to longer range (more than 10m) provided you design everything correctly, using higher I2c voltage level and lower value pull up resistors.

If the remote module is far away it is better to use RS485 or Ethernet to communicate with a remote I/O board that support common communication protocol. For example another FMD88-10 can be connected up to 1000meters away via RS485, or on the other side of the planet if communicate via the Internet.
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