Auto Metal cutting machine

Auto Metal cutting machine

Metal cutting machine Block diagram

 Over all the machine is something like the above picture.
While it run on manual it can does it job, no problem. (Run, Stop, Cut and repeat)

Problem: Right now the machine can not stop at preset length for cutting.

 At Auto mode, after preset all the length that we require and press the start button, the machine is keep running and did not stop to it required length for cutting.

The length is determine by this encoder.

Siemens PLC

 The encoder is wired to the PLC (PLC_224)as above picture and link to RS232 module (Simatic em232) just beside it.

Lenze-8200

Then the RS232 signal will communicate with Inverter (Lenze-8200) to control the gear motor.

Hydrolic cutter

Therefore, after the motor run to the required length it will stop and let the above cutter do the cutting.

Hitech 500S

Of cause, there is a Touch screen as above to keying the data.

Well! those are the operation of the machine, since it can not stop at it require length I need to check on the encoder and I found out that when it is running, there is blinking led light on the PLC which mean I guess the encoder is ok, right?
Then, I need to check the RS232 module to find out is this guy is good or bad. If this device is good then only I will check on the Inverter, right? But how am i going to check on the RS232 module (simatic em232) and the Inverter (Lenze-8200)?? Which i don't have much equipment with me. Or What is the best solution that you have that can solve the problem???
 If you are not clear about the problem, please email me to clarify.

Your vulnerable info is very much appreciated...