Item 4 is a Tstat8 on connected to a T3BB by RS485 main. I had a terrible time sorting out how to read the temperature from these when I first configured these. We spoke a bit about it at the time but I could never get it to work any other way. I am open to a better way if one exists but that does pull the temperature from a Tstat8.
Maurice: Set the protocol of the Tsat8 and the T3 controller to bacnet, then you can refer to the bacnet objects on the Tstat8 by instance number and bacnet object ID. Just like you have going on in lines 150 thru 230.
When I first tested the system I found that if for some reason a bacnet object cannot be read it will simply leave the variable at its previous value instead of dropping it to zero. I would much rather the variable was zero than a stale value or I would have no way to no the value was wrong. I added lines 20-140 to ensure that the variables are zeroed and then populated. If they cannot be read, they stay zero and I see the problem. If this was fixed at one point I didn’t notice but it absolutely was an issue when I wrote the program originally. I understand your concern about this but the program has run this way for months with no issue.
*Maurice: Just spoke with Chelsea, our developer here. She re-affirms what I was saying that when a thermostat goes offline, the network points will float along at whatever was last read. We’ll add some auto generated alarms for you so that when a device goes offline you will know about it. And I added to our big todo list is some commands to deal with offline devices in your programming. *
- 10 IF OFFLINE (Device Instance) THEN DO SOMETHING.*
Lines 240 and 250 are for two HUM-D sensors I have connected via ethernet. Ive never been able to get bacnet over ethernet to work at all. I tried and tried and simply gave up. I was able to read these sensors with modbus so I just left it. These lines too have been working well for months. I might look at this again if you think something has changed to cause this to be a problem.
Maurice: We just set up a test and can confirm that bacnet over IP to the humidity sensor is working fine. You may need to update some firmware for the T3 controller and HUM as some of this Ethernet routing and network programming is new.
I certainly dont want to ignore your recommendations when asking for help. I will try to implement the suggestions you have made and test to see if it helps. Im apprehensive to remove the = 0 lines unless the hanging variable problem has been addressed.
Maurice: Standing by to help, those initializing lines are redundant as far as I can see.
it might be unrelated but I just noticed the sensor in blue on the chart above seems to be reading wrong. Its and outdoor air temperature sensor from you guys. It looks like something happened at the time index just under the i in View 1. All the stats dropped out and at that same moment the OAT spiked way past a reasonable number. It never made it to 70F that day. The sensor is shrouded, on the shady side of the building with no real way to be artificially heated. It spiked up to 86F which is false at the same moment the Tstat8 data went away. This caused the boiler to fire since it thought it was way cold. The next time it happened was at the end of the View 1 box where the average gets “stuck” and flat lines out. That is what is bothering me. In that same time frame the Tstat8s were reading okay(red) but the average got “stuck” low.
Maurice: The network points look to be going offline intermittently. The jumps down to zero should not be happening, I would get those init lines out of your program for good measure. Chelsea is going to do a test to replicate this and we’ll udpdate later.
Im not sure whats going on really. We get some decent temperature swings this time of year but not that abrupt. OAT is going up 30 degrees F in minutes. OAT is read directly from a sensor connected to the T3BB inputs. I think something more is wrong here…
Maurice: No known issues with reading temperature sensors, pretty standard stuff as you can imagine. If there’s something weird going on with the power supply or grounding that could potentially cause some bad readings. You can rule this out by adding a fixed 10k resistor on an input, set the range to temperature and graph that along with the outside temperature. The 10k resistor temperature should stay flat at 25DegC.