Monitored dump valve wiring

Hi everyone!

I'm working on the controls design of a semi-automatic pneumatic vertical press. The machine will consist of two double-acting cylinders with 5/3 closed center valves and pilot-operated check valves on cylinders ports to keep them in position when no power is applied to the solenoids. Everything controlled by a non-safety PLC to automate the operation. An e-stop, light curtains and a dual dump valve hard-wired to safety relays (all dual channel) with auxiliary force-guided relays will be the safety devices.

The dual dump valve is a SMC VP544-X538 and has 2 safety limit switches for detection of the main position of the valves. I want to use these limit switches to achieve redundancy. Since I don’t have a programmable safety relay, can I wire them to inputs of the non-safety PLC?, or should I wire them to a safety relay? How is the logic that must be implanted for these switches?
I’ve attached a simple diagram illustrating the safety circuit i got so far to see how can I add them to my safety circuit. Any help will be appreciated.

use 1 NC from each dumpvalve


wire to safety relay > feedbackloop

ghostdog said:

use 1 NC from each dumpvalve


wire to safety relay > feedbackloop

Click to expand...

To a separate safety relay? Or to my e-stop safety relay?

feedbackcircuit of E-stop-safety relay


in series with NC of main-contactors


purpose:


check if dumpvalve's and contactors are both in off-state
before reset of E-stop.

ghostdog said:

feedbackcircuit of E-stop-safety relay


in series with NC of main-contactors


purpose:


check if dumpvalve's and contactors are both in off-state
before reset of E-stop.

Click to expand...

Thank you.
One more question. Then isn't necessary to use the other NC contact of the dump valve's limit switch to achieve redundancy?

Main E-stop relays also only use 1 NC


redundancy comes from 2x relay and 2x dump valve