How to chart relay commanded position #2366
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I have a 3-relay hat that I'm using in Indi AllSky to control heaters and fans. I'm able to select the fan status and create a chart to show me when the fan is on or off but I haven't been able to do the same for my heaters. This summer I haven't had much need of the heaters so I haven't worried much about them but as we move into cooler weather I need to confirm they're actually working as expected. Is there a way to do this? |
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Replies: 5 comments 6 replies
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What kind of HAT are you using? |
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I have a couple different relays hats I've been tinkering with. I still hope to get the 8-MOSFET board by Sequent Microsystems working, but I haven't been able to do anything with it. So, for now I'm using a mechanical 3-relay board by Waveshare. It's simple and appears to be well built and reliable. I've used this board in other pi projects with success. Attached is the fly sheet -- not sure its still available as their main webpage doesn't show it anymore. HAT tech changes fast. I'm using the relays to control fans and heater. Fans work perfectly. Its been hot so I haven't seen the heaters kick on but that time is coming. I find the heater settings in Indi AllSky a bit confusing, so a chart would really help me. If I have it wrong I don't want it to overheat and cause damage somehow. I've been testing the camera outside on a temporary pier/mount and am hoping to move the camera to a more permanent outside mount soon. I need to know I can count on my heaters first. |
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I see. I believe you can just use User Slot 1 to monitor the Dew Heater level. For a relay, it should just cycle between 0 for off and 100 for on. This should be similar to User Slot 4 for the Fan status. |
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That fixed the dew heater chart. Many thanks -- not sure how I missed that. I noticed the fans tends to oscillate (0/100%) a LOT as the system cools down at night. I asssume there's a way to add more hysteresis in the system to prevent that behavior? Would be best to leave the fan on longer and minimize relay cycling. A mosfet relay wouldn't be a concern but these little mechanical relays do fail. It appears maybe the threshold delta values could do that but I don't understand how they're used. I'm attaching a pic of my settings and the fan chart showing the fan level oscillation. |
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I just merged #2433 to add a hold time for the dew heater and fans to prevent fast oscillations between states. |
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With the dew heater now creating a chart it’s clear my heater is never working. While it’s been kinda warm, there have been cool foggy nights where a bit of heat might have been warranted. I guess I really don’t understand fully the config settings for the fans above, or for the heaters. Attached are my heater configs. I’m concerned I have both set incorrectly. Any suggestions ? 
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The settings look appropriate (at least they are not wrong). Since you are using thresholds, the Dew Heater will not turn on until the DHT22 temperature is within +3 degrees of the dew point. The dew point is a moving target since it changes with RH and temperature, so the numbers will change throughout the night. It may be more appropriate to set the low threshold to be 10 or 15 degrees, so that it turns on well before the dew point is reached. The dew point is a "general" target. Surface temperatures may actually deviate from air temperature due to evaporative cooling, etc and the surface of the dome could be cooler than the air temp. |
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I assume you’re suggesting I change the Low Threshold DELTA to ~15? I’m confused by the “delta “ label. This is the difference between which two numbers? Is it the measured DHT22 measured temp and dew point temp? If so, how is frost point used? Regarding the fan oscillations above, do you have any suggestions? As always, help is much appreciated. -Larry |
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Yes, the Low, Medium, and High values are deltas for the difference between the temperature and the dew point. A low threshold delta of 15 would mean the temperature would need be within +15 degrees of the dew point to activate. The frost point is not really used for any functionality. I will investigate a hysteresis for the oscillations. Changes will only occur every 15 seconds (the frequency of the sensor reads) so it will not cycle faster than this. |
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I tried to adjust the Delta Temperature parameters for the heaters and fan -- I though I might reduce fan relay toggling by having it turn on earlier. I had no issue making the suggested heater change, but I'm unable to get past the built-in error messages for the fan settings. My values satisfy the criteria as I understand them but allsky still won't accept. What am I doing wrong? I thought the high, medium, low values were used in a PWM system. With my relay driven system, only one of the three would be used. Do I understand correctly? Why are my entries being rejected? v/r, |
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I found a typo in the fan threshold validator. Merged #2376 |
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I see. I believe you can just use User Slot 1 to monitor the Dew Heater level. For a relay, it should just cycle between 0 for off and 100 for on. This should be similar to User Slot 4 for the Fan status.