CLICK Restart

[itsmoked]

I have a complex multiple state-machine PLC controlling a psychotic machine. Currently certain places can't be recovered from short of a power-cycle. The power cycle is torturous because several servo drives take forever to boot-up and they don't need to be rebooted. So, recovery takes about a minute, which is way too long to keep the production blood pressure's down. Is there any way to make a CLICK restart, essentially a warm-boot? Any suggestions welcome.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

Isn't the usual approach for this sort thing a watchdog, either hardware or software?

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[John2025]

You can stop and start the PLC through the programming port with the Click software, so there must be a command, but I don't know what it is or if it's documented.

 

[controlsdude]

I thought if a servo did not have absolute encoders, that the servo would have to go thru a homing sequence. If it loses where its position is at then it will rehome sequence. Are you saying that the servos have absolute encoders or resolvers?

Any switching from run to program to run on a plc will always cause a rehome sequence on servos. I would look at this part of program and change the program to see if you can rehome by slight movement. But also, if the plc loses some count that the servos use, you might have to save this during a switch to program in memory.

 

[John2025]

FWIW, we have an application where we use servos without homing them on power-up. Incremental encoders. We just need an accurate incremental move and holding torque between indexes. Admittedly a little odd. They're Kohlmorgen AKDs and you don't have to home them first if you don't need it.

 

[itsmoked]

IRstuff; The watchdog... Hmmm Interesting idea. I have to figure out a way to hang the PLC.. I must cogitate on this.

John2025; You make a good point. I wish the HMI C-More maker included this.

controlsdude; You are correct, if absolute encoders are not present. If you re-boot the servo drives you will indeed need to re-home them before they accept motion commands. This is part of why I'd like to just reboot the PLC as that avoids the slow and painful reboot of the drives themselves. I cannot issue the drives ANY commands for about 35 seconds after boot-up. They must be running windoz vista or something.. Once the PLC boots, it has to wait 33 seconds so the drives will listen, then it orders up HOMEs which take, worst case, 12 more seconds. I can live with 12 seconds, it's the 35 that make people think the machine is dead.

John2025; Oh? Indeed. I'm using the same AKD drives. I'm using a standard one and a completely optioned out BASIC one. I love every single thing about them except the absurdly long boot-up times. But alas it's not the homing as I've mention but the boot time that is getting me.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[John2025]

I couldn't agree more about the AKDs, good and bad. I'm not quite sure if their STO input(safe torque off) is sufficiently safety rated for your application. I've never had the guts/expertise to use it when the E-stop or guards are open. There's a guy named Gary at Kohlmorgen who's great. I'm not sure I should name him in the open, but maybe you already know him, or is there a way to private email each other on this forum?
John

 

[itsmoked]

Hi John,
We can't pass emails on this site but whenever someone has a tag-line link you can bet there's a way to contact them via that.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[John2025]

E-mail sent. I forgot there's actually a world outside of the Midwest so I don't know how much good it will do you. I was in Santa Cruz last year on vacation, you lucky dog.

 

[controlsdude]

35 second timer sounds like some default parameter in the servo drives or possible some init sequence that the original programmer put in on this machine. I would look at the init routines in that machine with the servos. Or hold a signal high on your side when your resetting on your side. Is the interface ethernet, hardwired, or some other comms? I know on some IO cards you can hold an IO card output/input in a certain state when switching from run to program to run.