Interfacing 24VDC output with 5V TTL input
Judging by the Schmitt trigger symbol in the receiver this module will output a 'high' when the input is on. You want the reverse. You could use an open-collector transistor to do this or you could reverse the output logic in the PLC. Connect up to your +5 V and 0 V and wire OUT to the TTL input.

Alternative solutions:







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. Three options.


(a) A small relay gives isolation and easy fault-finding. Use one designed for signal-level currents. These work well if frequency of operation is not too high.
(b) An opto-isolator has no wearing parts and can handle high frequencies.
(c) If isolation is not required a simple open-collector transistor will pull down the TTL input.




Figure 2. Use a DIN rail component carrier to make an industrial standard custom module for your interface circuits.



From the comments:


  So by using a reverse PLC logic, when the output of the PLC is low (ergo the device is not "activated" it should pull the input to GND).


Be careful here. You need to ensure that your solution can't put 24 V DC onto a 5 V input. A typical 24 V PLC output will give 24 V or nothing - and nothing means open-circuit, it doesn't mean 0 V. You need a level converter (24 V to 5 V) and then you need to check your logic is the right direction. Since the PLC is active high and TTL is typically active low you may need to invert the logic. If the interface will do that you don't need to do anything else. If the interface won't then have it done in the PLC logic.