How to wire digital outputs?

ACE digital outputs are NPN transistor outputs. NPN Outputs = Negative logic.

The logic is the following:

  • When the  OUTPUT  = 1, we link the output to the  (-)  GND (-)
  • When the  OUTPUT  = 0, the output is linked to almost nothing! (in reality, to the  (+)  terminal pin via a 33K ohm resistor)
Your load (here, the indicator light) must be connected to:

  •  OUTPUT 
  • VDC (+) 


The ACE outputs are connected:

  •  (+)  > VDC (+) 
  •  (-)  > GND (-)
  •  OUTPUT  > Your load

  • VDC (+) is the + of your power supply. From 5 to 24 VDC.
  • GND (-) is the – of your power supply.
  •  (+)  it is often the last pin of your connector
  •  (-)  it is often the first pin of your connector
  •  OUTPUT  is an output of your ACE PLC


How to wire the output to a relay or an indicator light?

Don’t forget to wire the  (+)  to the VDC (+). It is used to eliminate the current feedback of inductive loads (electromagnet, contactor coils, relays,..)

to a relay

to a indicator light

Read more: How does the outputs work?

Each output is connected, through a 33K ohm resistor to the VO terminal pin (next to output 6). This acts as a weak pull up. When the output is off (logic state 0), the output will be pulled up to the voltage at the VO terminal.

If no power supply connection is made to the VO terminal, the voltage at the VO terminal will come through a 10 ohm resistor and an isolation diode, resulting in a voltage approximately 0.7V below the 5V supply to the PLC. This is enough to allow the PLC outputs to directly interface TTL circuits.

If voltage is connected from an external source to the VO terminal, inactive outputs will pull up to the external source voltage.

If AC power, or higher power DC needs to be switched, the Ace’s digital output ports can be connected to a Relay Terminal Block module, through a short standard cable, supplied with the module. With a Relay module, up to 250VAC and 5 Amps can be switched under program control. The cable diagram connection to the PLC digital output port pluggable connector is illustrated in the Relay Terminal Block module documentation.

How do I connect my output to a PNP input?

You can add our Optocoupled Sourcing Transistor Board TBTN06-35H (see our Shop page)

Or… Add a pullup resistor of 2.2 kΩ… But in this case the logic will be inversed.

For reverse the logic of output in your program, add this program (example for outputs D and E outputs) at the beginning of your main program:

Here, we reverse the logic of 12 outputs (D1..D6 and E1..E6) by additing 255 with the Xor function of the Calculator tool.

You can named each “ROutBitXn” by any name you want.