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Hi all,
I have an existing PC based watering system for our commercial nursery using ocelot and bobcats for measuring temp, RH etc. Existing output for valve control uses relay boards driven directly from the computer.
I have intended to expand the relays using a remotely mounted Rly8-xa unit and had purchased one some years ago but haven't got around to trying it until last week.
Appeared to install and operate ok using CMax & cpuxa but stopped working after a time, half to one hour. While it was working the Active led was on solid, the Comms led blinking as normal for communication. On failure, the Active led was off and the Comms led on solid.
I don't understand the manual regarding the watchdog settings. The manual indicated the timeout for the watchdog is set using parameter #0 but there doesn't appear to be a parameter #0. I saw a web reference that the setting is actually parameter #5 and that value for this unit is 255 which is the watchdog off setting and I understand the default setting, so presumable the problem is not a watchdog timeout. I would assume this should not happen while communication was available even if there was no messages being sent to the rly8-xa.
I noticed the heat sinks (voltage regulators?) were quite hot, too hot to touch. Power supply to the unit is from a regulated 4A DC supply nominal voltage 13.8V, measured 14.06V. This is within the nominal 16V max as per specifications but I did see discussions indicating possible overheating if the voltage is too high. This power supply is the one powering the ocelot, bobcats and fans in the bobcat enclosures and has been working for some years without a problem.
I also notice that interference can be a problem with these units, mainly from valve coil spikes. For test purposes I had connected the unit adjacent to the computer without any connections to the relay contacts.
To test the over voltage problem, I fitted an adaptor to drop the voltage. The unit failed after a time on 12v and yesterday, again after a longer time, on 9v. Today it has run all day on 9v without any problem. At the moment, the regulator heat sinks are relatively cool, barely warm to touch but they seem to go to very hot quite quickly on failure.
Any ideas?
John
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