Need help with a Boy 15s

I have a Boy 15s injection molding machine. I added a PLC and I am manually going through the movements at this time. However, I cannot get the screw to retract. It will rotate fine and hot plastic will extrude out of the tip. There are 10 solenoids on this machine. I have added 10 buttons to activate each solenoid regardless of the limit switches. s3 will push the screw into the barrel. s17 and b18 cause no motion but I believe b18 will drop the injection pressure. I can hear the solenoids click when activated. Any help would be appreciated. Thank you in advance.

graemeian

a little late to the party but am wondering if you got the Boy functioning properly? the unmelted plastic is what drives the screw backwards till it hits B14 micro switch if memory serves me right. No way to hydraulically move screw backwards on mine. Unless maybe your machine has a screw retract suck back feature?? I'm interested in your PLC mod as my Dipronic control is acting up. How hard was it to install and a ruff price to convert? thanks, rj in Walla Walla, wa