TTL & CMOS logic controll signals

Dear Forum
Do PLC manufacturers have specific commands / modules for input and output of standard TTL &(+5vdc) CMOS (+16vdc) control signals that are used to send a recieve control signals into integrated sub-systems hardware. I know that there are transistor and DC I/O modules but these all seem to be either for driving things or recieving sensor inputs. What about good ol' low current logic state intefacing ie. 74 series etc.



Cheers
PaulS

Some PLC manufacturers have them. They call them 5 volt or 5-15 volt modules.
The inputs are Optoisolators. Once I modified an Automation Direct module rated for 24DC input. The dropping resistor was 2200 ohms. I needed TTL for 2 of the inputs, so I changed the 2 resistors to 680 ohms. Normally, I would use the D2-32ND3-2 module.
The transistor output modules are also optoisolators, but some need the 24DC to power the output circuit. The closest I see is the 12-24 volt modules. That will work for CMOS, but you may need high current pullups to drive the opto's. Ive used relay modules for 5 volt outputs, sinking format to help with noise immunity.
Outside world interfacing will always be isolated (opto or relay) to protect the rest of the PLC. In the PLC world, an accidental short to 120vac blows only the module, not the entire system.

Go here to look at the modules for AD's DL-205 series PLC's.

Allen Bradley has TTL Input and Output cards for their SLC and ControlLogix line of controllers.

Omron also have TTL cards.