Studion 5000 & Kinetix 5700 - Safely limited speed

[MartinK 0]

Hello there,

I am using a Kinetix 5700 drives to control bunch of axis.

HW used : 5069-L320ERMS2 GurdsLogix, 2198-S086-ERS4 Servo Drive with MPM-B2152M-M motor and the 843ES-SIP12BA6 safety encoder.

All is working fine except I can't figure out how to dynamically change an axis velocity  controlled by a MAG instruction.

I have a virtual master axis controlling the velocity and each physical axis is controlled by a MAG instruction with a gear ratio.

In my safety program I have SFX and SLS function block used to determine the safe speed limit. The  SLSLimit output of the SLS function block is linked to a SS1 Request of my servo drive. This causes the axis to stop when safe speed limit acceded. 

What I'd like to be able to do is to dynamically change velocity (limit it to safe speed if SLS instruction is active) of each axis without having to change the gearing ratios and thus avoid the SS1 safe stop action. 

I know how to do that using JOG or MOVE but is it even possible to do that using the MAG instruction?

Regards Martin

[BobLfoot 301]

I may be reading your post entirely wrong.  But wouldn't you adjust the velocity of the Virtual Axis to reduce the velocity of the slaves?  

It would seem to me also that Safety Function is meant to Stop not warn.  You may want to craft some parallel logic reading the slave axis velocity and reducing the virtual axis velocity as you approach safe limit.

[MartinK 0]

Well I see what you're saying. Yes if I adjust the virtual master every axis will slow down according to its gearing ratio, that however, doesn't guarantee that the lave axis will slow down under the safe limit and therefore I'm still running the chance that the machine will stop. That is, of course, the safety compliant solution and that's also what will happen now. The idea to limit the speed comes from this presentation I found the other day. I've tried it with JOG command and it works.

As I'm writing this reply I'm realizing that I could actually work-out the biggest gear ratio and if I lower the master enough to drop under the safe speed limit of the fastest axis I'll achieve what I need.... I'll try that....

Thanks