VELMEX VXM-3 - AppendixN; Limit Switches and Home Switches

Appendix N
Limit Switches and Home Switches
6
TheVXMbydefaultrecognizesnormallyclosed(N/Ctorun)limitswitches. Thedefault
modeisauto-detectnormallyclosedswitches. IftheVXMisusedwithnormallyopenor
withahomeswitch,thelimitswitchmodewillneedtobechanged. Thefollowing
commandsetstheoperatingmodeofthelimitswitchinputs.
VHW/P0[
getLmM
=motor#(1,2,3,4)
=motor#(1,2,3,4)
SetLimitSwitchmodeforaxism,m
m
x
0=Auto-detectN/Ctorun(default)*
1=EnabledN/Ctorun
2=DisabledN/CforHomeSwitchuse
-1=EnabledN/Otorun
-2=DisabledN/OforHomeSwitchuse
,
value
Get
LimitSwitchmodesettingforaxism
returnediseither -2,-1,0,1,2 (default=0)
Itisimportanttounderstandhowahomeswitchworks,andwhatprogrammingprocedure
tousetogetahighdegreeofprecisionandaccuracyobtainablebytheseswitches.
Repeatabilityof 1motorstepisachievableiftheproperproceduresarefollowedwhen
referencingtoahomeswitch.
Themostcommonhomeswitchusedonrotarytablesisamagneticreedtypesensor.The
magneticsensorisusuallyconnecteddirectlytothepositiveandnegativelimitswitch
inputsontheVXM.
Homeswitcheshaveanactiveareaofseveraldegrees. Becauseofthislargeareawhere
theswitchisactivated,itisimportanttoalwaysapproachtheswitchfromthesame
directionwhenhoming.
Sensor
Magnet
Activated Area (20 B4800 Rotary
30EB5990 Rotary)
Rotary
Table
Using Home Switch on Rotary Tables
Limitswitchinputsareoptically
isolated,fromthemaincontrollogicof
theVXM,asshowninthediagramat
theright.
VXM
+24V
10K
External
Limit
ToMCU
2xpermotor