5i25 + 7i74 + 7i71 communication errors

Yes but load is under 60mA. And datasheet mention that with loads under 60mA flyback diodes are not needed. How do I get complete error posted here?

if this is RTAI, the error messages are logged to the kernel log (viewed with dmesg)
If this is Preempt-RT, the messages are logged to the terminal (start LinuxCNC from a terminal window)

The 7I71 driving a 36 mA coil is fine without flyback diodes _BUT_ if the relay contacts
switch an inductive load, they must have arc suppressors

Hi,

These do drive 110VAC hydraulic valve solenoids. And currently no Arc Supressors. Do you know where to get arc suppressor modules with about 10-20 inputs?

I dont recall seeing multiple channel units, the ones I'm familiar with are like this:

www.alliedelec.com/red-lion-controls-snub0000/70030263/

or this:

www.mouser.com/new/cde/CDE-Quencharc-snubber-networks/

Edit: the "Red Lion" part is actually this:

www.onlinecomponents.com/okaya-electric-xeb0471.html?p=12040652

Old control that was removed from this machine had few 10 input units(big black boxes with screw terminals). I still have those boxes somewhere I have to check if those can be reused.

Tero

Hi,

Ok good news is I found those modules. Bad news is that these are mostly broken ones. So I will toss them into trash and forget. Now I have resistor size it is 225 ohms(5W). I still need to find out cap size before I can order new ones. Anyone know how to find that out?

Tero

You could short out one of the resistors and use a multimeter with capacitance range
(225 Ohms is low enough that it might read fairly close without shorting the resistor)
or use a RLC bridge if you have access to one

If you are adventuresome and have a multimeter with a AC mA range you can measure like this

120VAC L1 --> suppressor common --> suppressor(1) --> multimeter AC mA -->120VAC Neutral
and calculate the capacitance from the AC current

Ok

Value was measured with LCR and it was 2,0 uF I could not locate arc supressors with 2uF/220Ohms. So I ended up with these from Farnell. I required a plastic module with screw holes for nice installation and long wires. After installing these communication errors seem gone Thank you for help.

Not only will the Arc suppressors reduce radiated EMI,
they will also make your relay contacts last much longer.