Analog output on T3 stuck off after reboot

I have a T3-BB, hardware version 29, MCU version 64.6 (latest, I think).

One of the analog outputs controls a fan with a 0-10v speed controller. It is controlled by a simple program:


FANCTRL is the analog output
PID1 is a PID loop
MINCTFAN is an analog value
OVNSPD is an analog value

The program execution time is 3ms so I don’t suspect a loop.

Here’s the output when it’s commanded on (screenshot follows)

Everything works perfectly, until I reboot the device.

When the device reboots, the analog output is commanded on as shown in the T3000 software, but the actual output stays off. If you move the hand/off/auto switch from auto to off, then back to auto, it immediately starts outputting the correct voltage.

I’ve recorded a video of this happening there:
Problem with T3000 controller outputs on reset - YouTube

Unsure what’s happening here - would appreciate any insight folks have on what might be causing this. Thanks!


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As I was saying in the email, the first thing to do when something just doesnt make sense is to do a firmware update and while you’re there do an update of T3000 itself. You can do both operations in the T3000 → help → check for updates dialog.

For misbehaving outputs, the next thing to check is to test the output in manual mode. Use the hand off auto switch and check the output state, watch what happens at Tab2 as you do this. Also you can use the PC to toggle the output state, set the HOA switch to auto and then at Tab1 set the output to manual mode. Toggle the output at Tab3 in the value column.

For analog outputs make sure the range is set to something simple like 0-10V at Tab4. Make sure the Low and Hi volts are set to the defaults of 0 and 10V, there should be no values showing at Tab5.

Disconnect any output device like a relay or damper motor. The field device could be interfering with the output signal. One common problem is 24vac is switched around in the system somewhere, it could be any device including other controllers in the system or damper motors/valve motors. Remove all the input and output plugs and the network cables to totally isolate the T3 controller to rule this out.

If you cannot get the outputs to behave using these tips then the hardware is likely blown. Try moving the output to a new output position assuming you have some spares. If not you will need to send the hardware to Temco for rework, its free but we do ask you to pay the shipping.

Very helpful, thank you.

Confirmed I’m on the latest version.
Confirmed that the hand off auto switch state is properly reflected in column 5.
Set the analog outputs as you directed, no values in columns 9 and 10.
Disconnected everything to isolate the controller.

I also discovered this is happening with the digital outputs as well. After a reboot, you cannot command them on until you toggle the hand off auto switch from auto to off.

Also seeing an interesting behavior when I try to manually command them on. Sequence to repro is:
a. Set hand-off-auto switches to “auto” on digital and analog outs
b. Reboot device
c. Leave hand-off-auto switches as is, in “auto”
d. Note correct state of hand-off-auto switch in HOA switch column.
d. In software, set auto/man to “manual”
e. In software, set value of digital output to “On”
f. Note the output will not switch on
g. Wait for a refresh, then note the manual value in software has reverted to “Off”

Isn’t it strange that the manual software setting is essentially rejected by the hardware? Why would that be? Anything else I can try here?

From what you describe it seems that there is an external master controller setting the output at a higher level priority. This is a rather complicated feature of Bacnet for allowing external masters to control outputs of remote devices.

You can learn more about it here:

Can you check the priority array of your device as shown here:

Or you can clear the device to go back to the default priority level where the device itself is in charge of the outputs.

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