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I'm using a non-linear 24VDC, 10 amp power supply by SOLA (spelling?). It's used to power the following:
A) 2 motion controllers
B) 24 relays (24VDC relays that switch 110VAC to hydraulic & pneumatic cylinders)
C) 1 operator interface
D) 20 or so Bimba reed switches (3 wire switch configured as PNP)
E) 50 or so proxes from Turk (PNP, inductive & capacitive)
F) 40 or so proxes from P&F (PNP, inductive)
G) Control power to 2 servos (maintain encoder position during E-Stop)
H) Drive status to 4 servos (NO relay determining whether or not drive is
enabled)
I) 4 brakes (130mA
J) Monitor circuits for MCR & 8 motor contactors (230 single & three phase)
Everything in the system seems to working perfectly except the Bimba reed switches & the P&F proxes. The Bimbas are wired into a PLC & the P&F proxes are wired into the motion controllers as overtravels on ballscrew tables. The PLC has no problem seeing the input signal, but the LED on the switch itself is going nuts. It's on, it's off, it's flashing, it's not
flashing, etc. The P&F proxes also have LEDS, but they don't go nuts.....they just quit working. All of a sudden they'll just quit working (they're NC switches that "freeze" open). There are quick disconnects on all switches.
I've put a scope on the power supply in the panel & it looks good. All the switches come straight into a small junction box. At the box, we tie all the 24VDC & -24VDC power connections together via terminal blocks. We then bring only the signal (load) wire back to the main panel. The 24VDC power signal in the junction box looks good & clean. The distance between the main panel & the junction box is about 15 - 20 feet. The
distance between the junction box & the devices is about 10 - 15 feet. I took a look at the power at the switch itself & saw some 5 - 10 volt spikes at divisions of 1 microsecond and faster. The fact that I didn't see these spikes at a slower division level explains why the PLC & motion controllers aren't seeing the fluctuations (both have a debounce time of at least 1 millisecond).
We contacted the manufacturers & really didn't get an answer. So far we've lost 3 P&F sensors in less than 3 weeks. The Bimbas haven't failed,
but the disco light show from the LED's is very annoying (sometimes the LED will stay out for 5 or 10 minutes, even though the switch is actually
made).
Thoughts, suggestions, comments? By the way, I am using fly-back diodes on the relays & brakes.
Thanks,
Guy
PS. I've posted to this list in the past as a distributor for automation products. Thanks to words of encouragement & advise from many of you, I've left distribution & joined 2 other guys to form an integration company. It's much more fun "playing" with the equipment than selling it.
Guy H. Looney
Motion Control Engineer
A.C.E. Systems, LLC
170 Medearis Drive
Old Hickory, TN 37138
email: [email protected]
website: www.acesystemsllc.com
work: (615) 754-2378
fax: (425) 944-5017
cell: (615) 330-0044
A) 2 motion controllers
B) 24 relays (24VDC relays that switch 110VAC to hydraulic & pneumatic cylinders)
C) 1 operator interface
D) 20 or so Bimba reed switches (3 wire switch configured as PNP)
E) 50 or so proxes from Turk (PNP, inductive & capacitive)
F) 40 or so proxes from P&F (PNP, inductive)
G) Control power to 2 servos (maintain encoder position during E-Stop)
H) Drive status to 4 servos (NO relay determining whether or not drive is
enabled)
I) 4 brakes (130mA
J) Monitor circuits for MCR & 8 motor contactors (230 single & three phase)
Everything in the system seems to working perfectly except the Bimba reed switches & the P&F proxes. The Bimbas are wired into a PLC & the P&F proxes are wired into the motion controllers as overtravels on ballscrew tables. The PLC has no problem seeing the input signal, but the LED on the switch itself is going nuts. It's on, it's off, it's flashing, it's not
flashing, etc. The P&F proxes also have LEDS, but they don't go nuts.....they just quit working. All of a sudden they'll just quit working (they're NC switches that "freeze" open). There are quick disconnects on all switches.
I've put a scope on the power supply in the panel & it looks good. All the switches come straight into a small junction box. At the box, we tie all the 24VDC & -24VDC power connections together via terminal blocks. We then bring only the signal (load) wire back to the main panel. The 24VDC power signal in the junction box looks good & clean. The distance between the main panel & the junction box is about 15 - 20 feet. The
distance between the junction box & the devices is about 10 - 15 feet. I took a look at the power at the switch itself & saw some 5 - 10 volt spikes at divisions of 1 microsecond and faster. The fact that I didn't see these spikes at a slower division level explains why the PLC & motion controllers aren't seeing the fluctuations (both have a debounce time of at least 1 millisecond).
We contacted the manufacturers & really didn't get an answer. So far we've lost 3 P&F sensors in less than 3 weeks. The Bimbas haven't failed,
but the disco light show from the LED's is very annoying (sometimes the LED will stay out for 5 or 10 minutes, even though the switch is actually
made).
Thoughts, suggestions, comments? By the way, I am using fly-back diodes on the relays & brakes.
Thanks,
Guy
PS. I've posted to this list in the past as a distributor for automation products. Thanks to words of encouragement & advise from many of you, I've left distribution & joined 2 other guys to form an integration company. It's much more fun "playing" with the equipment than selling it.
Guy H. Looney
Motion Control Engineer
A.C.E. Systems, LLC
170 Medearis Drive
Old Hickory, TN 37138
email: [email protected]
website: www.acesystemsllc.com
work: (615) 754-2378
fax: (425) 944-5017
cell: (615) 330-0044