Output is Open Collector for Arduino 2560?

What is the output type of the Arduino 2560? I have an application to interface with the PLC. This operates at 24V, can I use the output of the Arduino as an open collector directly, as shown in the image below?

Absolutely no. The 2560 processor has a data sheet. Please download it from Atmel and read it.

No, you need to buffer the Arduino output to do that.

(24V - 2.5V LED Vf)/(51 ohm + 51 ohm) = 210mA, so you may need an additional series resistor to keep from damaging the optocoupler. ULN2003 or ULN2803 could be used as a multigate buffer.

Either that, or get rid of the pin 35 to 17 jumper, and connect 35 to 5V. Then (5V - 2.5V)/102 ohm = 24.5mA which is reasonable for an Arduino output to pull low with an output pin.

One idea:

New-Project(2).png

CrossRoads: Either that, or get rid of the pin 35 to 17 jumper, and connect 35 to 5V. Then (5V - 2.5V)/102 ohm = 24.5mA which is reasonable for an Arduino output to pull low with an output pin.

This.

aarg: Absolutely no. The 2560 processor has a data sheet. Please download it from Atmel and read it.

Really? Its huge. The pertinent information is the electrical specifications for the pins which has limit of -0.3V to Vcc+0.3V, like every CMOS chip.

For the 2560, it's +/- 0.5V.

Voltage on any Pin except RESET with respect to Ground ................................-0.5V to VCC+0.5V

Outside of that there is the risk of damaging the diodes that clamp the voltage to Gnd and Vcc.

Some CMOS chips quote 0.3V, some 0.5V, never quite sure if thats for any deep reason.

Its not just the risk of damaging the diodes, its the risk of CMOS latchup (which can trash the entire chip).

MarkT: Really? Its huge.

That's why it has an index.

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