bigjoe Posted July 8, 2005 Report Posted July 8, 2005 Hi just learning plc and I made this simple program from medoc: x0 x1 --l l---l/l---------------(m0) m0 l --l l-l m0 --l l---------------------(yo) after doing so I save it and transfered it to the plc, after transfering, I started doing the wiring and after that I push ON the button for X0 and there is no output at all. I check the wiring it all seems correct. Did I miss something? johnny Quote
bigjoe Posted July 8, 2005 Author Report Posted July 8, 2005 the wiring on the input goes like this: PLC Input: com-----PB(NO)------X0 com-----PB(NC)------X1 and on the output goes like this: PLC Output: +V-------RELAY----(com0-Y0)--------V- com0 and Y0 terminals acts like a NO swicth. regards, johnny Quote
navillusi Posted July 8, 2005 Report Posted July 8, 2005 The mistake I believe you are making is that your X1 is a normally closed switch (I assume a stop button) the device in the program is a negated contact. Thus it will be true when the input is 0 (switch pressed) From the looks of it, if you hold the stop button in and press the start then it will work? Change the ]\[ to a ] [ for the X1 Do not confise a negated contact in the PLC with a normally closed contact in the outside world, they are different! Quote
rajsiyer Posted July 8, 2005 Report Posted July 8, 2005 Yo Johnny..... Yo doin alright man. Jes change the XIO(symbol for NC) at X1 address to XIC and work your baby will. Have fun. Old Raj always happy to help Quote
Sergei Troizky Posted July 8, 2005 Report Posted July 8, 2005 Ensure that: - The PLC Run light is On. - No Error light On or blinking. Connect the S/S input to + (that is configure inputs for sinking signal). Connect COM0 to -. Quote
bigjoe Posted July 9, 2005 Author Report Posted July 9, 2005 Hi thanks guys for the replies! I knew it that my mistake was the NC contact that I wired on X1, it's because there is an initial signal coming from it tha reverses the logic on the ladder right? Thanks, johnny Quote
Crossbow Posted July 12, 2005 Report Posted July 12, 2005 Don't think of -][- and -]/[- as normally open and normally closed. The best way I can explain it for beginners is -][- is looking for the input to be ON (true) and -]/[- is looking for the input to NOT be on. I explain it as a NOT contact in my classes and everyone gets it. -]/[- actually passes power when the input it's addressed to is OFF. Quote
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