GE Fanuc Series One

[elevmike]

Ok, so I'm having a little trouble with this rung:

|

| << RUNG    3 >>

|

|  012     013                                                             160

+--] [-----] [--+---------------------------------------------------------(   )

|               |

| T 600   T 601 |

+--]/[--+--]/[--+

|       |       |

|       |  160  |

+       +--] [--+

|                

|

As I see it the instruction are as follows:

0006 STR 0012
0007 AND 0013
0008 STR NOT TMR 0600
0009 AND NOT TMR 0601
0010 OR 0160
0011 AND STR
0012 OR STR<note this one here!!
0013 OUT 0160

However Gary's program reads as follows:
0006 STR 0012
0007 AND 0013
0008 STR NOT TMR 0600
0009 AND NOT TMR 0601
0010 OR 0160
0011 AND STR
0012 OUT 0160

So, am I missing the boat, or did Gary miss a line??

Mike..

 

[Steve Bailey]

My mistake. The rung should look like this.

  12    13     T600   T601       160

--] [---] [--+--]/[---]/[--+-----( )-

             |             |

             |  160        |

             +--] [--------+

 

[elevmike]

Ok so look at that rung in relation to the two timers. Hmmmm... Somebodys using a PLC for a two handed safety run station..

So Gary what have you got?? A press, or a shear? Dont count on that PLC for safety!!! Not at all a good idea!!

 

[Steve Bailey]

Good call Mike. Definitely a cause for concern. Gary, what is wired to inputs 12 and 13? That would be terminals 2 and 3 on the module two slots to the left of the CPU.

 

[elevmike]

I dont know if he's registered.. I'll shoot him an email.

 

[Gary Sparls]

Mike,
I will check into the wiring of the press in question. I have only started to work on this and am not familiar with all aspects of the press. Thanks for your input, it has been a great help.
Gary

 

[elevmike]

Gary,

As you probably already know, the first three rungs have to do with a two button safety start. The idea is the operator requires both hands on the start puttons to start and run the press, there by preventing his hands being in the wrong place at the wrong time.

It is ok for the PLC to do a redundant operation, which may be the case here, but it's not ok for the PLC to be the only safety device. It is possable that each button has a second set of contacts that activeate another safety circut for running the press.

Question: Do you have a wiring diagram for the machine?

 

[Gary Sparls]

Mike,
I checked the press close switches and they are not wired into the actuator for the press although there is a gate switch wired in series with the output to the control solenoids. Is this sufficient protection?
Gary

 

[elevmike]

Gary,

By that do you mean that there is a gate seperating the operator that must be closed to activate the press? If so that makes it better/safer. However, technically the buttons should also somehow be wired in series with the gate and solinoids also. I cant see the machine so it's not for me to make a judgement call on as to let it go or not. But from an OSHA type of view, your press is not in compliance. From a realistic point of view the gate switch may provide adaquite protection, but picture this. PLC malfunctuions and run output on PCL is locked on, (contact welded closed or SCR shorted). Gate is closed, so press keeps cycling, beating product to a pulp. Nobody hurt, but a lot of damage to product, dies, and press.

Do you have a wiring diagram you can post, or email to me?

Mike.

 

[Gary Sparls]

Mike,
Sorry, no I don't have wiring diagrams, the machine is old and has been set up by many different people no longer working here. The press only has one close per cycle and there is an emergency stop button to shut off the hydraulic pump in case it is needed. The operator does need to hold both press close switches until the cycle starts which is done with a limit switch that turns on input 0020 when the press reaches the top of its stroke so I don't see any chance of hands getting in the way.
Gary