Input light on Apha not reseting

[captmike41]

We have a rush job that has to be done by Monday 8o am and for some reason we can't rest input 4. We've even disconnected the stop switch and it doesn't do any thing. I was thinking it my be a ground issue because just before this happened we had some z movement issues. Any suggustions would be appriciated.
We e-mailed shopbot but no one has called or e-mailed back. Anyone have a phone number of a tech?

Mike Ferris Godfrey enterprises 724-845-1499
captmike41@aol.com

[gerald_d]

http://www.talkshopbot.com/forum/mes...tml?1151153465

First read the above thread (only 2 days old)

When you are finished kicking yourself, reconnect your switch, and twist it to unlock.

On recent SB models, the E-stop opens the circuit when you push it in. Disconnecting it also gives you an open circuit. For the SB to work normally, you want to have a closed circuit - same as a jumper wire from pin 4 to ground.

From a safety viewpoint, is there any reason for an SB to have a lock on the E-stop? Our old SB does not re-start when the E-stop is released and so it does not need a the locking style button. SB could save a few dollars and lots of service calls by using a simpler switch.

[captmike41]

Thanks, I read that one before posting. Turns out we had a ground problem to the y and z carriages. I ran a new cable and we're back in business. back to routing.....thanks

Mike

[gus]

They put a latching switch on there because:
Start here
http://www.manufacturingtalk.com/news/sie/sie133.html
EN-418 standard, NFPA 79 standard, OSHA. My guess would be that they figure that once
you hit the E-stop it should stay set and maybe you should think twice about restarting the thing.
It takes a deliberate act to restart with a latching switch.

[gerald_d]

Ted, if memory serves me right, the latching is needed for E-stops in remote locations. The raised red button on your table-saw probably does not latch. I am not up date with all the specs, but a lot of modern equipment from reputable suppliers has non-latching stop buttons.

What is actually of more concern to me is that the SB E-stop is connected only to the control board and relies on a connection to signal ground. So, if the control board shorts out, what shuts down the router/spindle or carriage movement?

[gus]

Not the same red button. There are stop buttons and e-stop buttons and they do not provide the same function. As I can tell by your second statement about your concern as to how the e-stop is connected.

Your concern is not unfounded. I would like to see the e-stop contacts directly in the control loop for the relays for the router/spindle and drivers.
I like e-stops to kill things dead without going through some logic board to do it. This link here may show some light on how stuff happens or where am I going and what am I doing in this handbasket.
http://archive.metalformingmagazine....4/chaos497.htm

[richards]

Emergency Stop bottons have been a source of arguments in the process control world since I joined in the mid-1970's. The 'brute-fource' school of thought wants the E-switch wired as part of a self-latching relay/contactor that controls all power entering the control box. The 'nominal' school of thought wants a normally-closed input that when open, causes a software controlled shutdown (which, as Gerald pointed out, could fail if the control board malfunctioned).

Personally, I favor the 'brute-force' method. Turn on the power with a fail-safe switch. Latch the power on via a reset switch that activates a self-latching relay/contactor. Route the coil circuit of the self-latching relay/contractor through the E-switch. Thus, if the E-switch is in its tripped state, the self-latching relay/contactor will never latch and the control box will not have power going to it.

[gerald_d]

As you say Ted, not the same button...

On my SB, the so-called E-Stop turned out to be just a Stop and not an E-Stop. Calling it E-Stop and making it latch doesn't change the function. I am also in the school which days an E-Stop stops everything as fast as possible. It must kill all the power sources and not just fiddle with control signals.

[gus]

The latching thing is not a big issue if you are the only one ever in the area of a machine. But when you have more than one person around it can be a problem. I may be on the back side of a large machine that enters the self destruct mode. I push the E-Stop (one of several) and the machine shuts down. The second person on the other side by the main control box wonders why the heck the machine shut down and hits the start button. Now depending on how you have the control circuit set up if my E-Stop is latched it will not restart until I have cleared the fault and reset the E-Stop. I am sure you have been around enough equipment that could squash you like a bug to know why having a latching E-Stop could be a good thing.

[gerald_d]

Believe me, I am a big supporter of a latching E-Stop, but then it must be a true Emergency stop that is seldom used.