We have a mid size school district with six schools which are predominantly Automated Logic.
I’m currently working on a project replacing 7 Mammoth Multizone rooftop control packages.
The larger units have up to 12 zones, 36 UI 6 DO 16 AO.
Using a T3-8o to test bench the setup using a ALC router to Bacnet/MSTP.
Funny issues with the T3-8o. If I use the T3000 software over Ethernet, the MSTP network
stops communicating and the device shows as offline. Makes it a little difficult to change IO
config and confirm at the same time.
Another issue is the BAPI t’stats that exist on the job. 3 wire 10k-2 with warmer/cooler sliders. Try as I might, sharing the common from the sensor and the slider doesn’t seem to work. The T3 just reads 0. The slider is 15k to 35k. Using a meter, I see that every Space temp scan on the input brings the reading to a direct short on the slider input.
Sharing the common doesn’t appear to work. I’m looking for any input on how to accomplish this with the existing 3 wire system.
For intermittent communications issues the only thing I can suggest is to be sure to update to the latest & greatest firmware for the device itself, you can do that under T3000 → help → check for updates → download firmware and update device. While you’re at it do the same for the T3000 front end itself even if you dont normally use it to manage the system.
For the MSTP issue, could you show me what you have set up here. There is a known issue with configuring two MSTP ports which we’re working on, for now only one MSTP subnet is supported at a time. You can also check the subnet network health as shown, have a look there for clues.
For the 3 wire issue, it should work fine to share the ground between the sensor and the slider. Send on a screen shot of what you have set up for the slider range. I would expect to see a custom table for something like below. The 35k resistor will need a pullup resistor for excitation voltage which is done by setting the range and signal type at Tab1. Then fill in the scaling from 0 to 3V for the slider, here I set it to provide an offset of plus 3 to minus 3 DegC/F.
Full scale voltage for the thermistor/dry contact is 3V, you’d have to know that to get this working which is a bit sneaky I admit. I’ll get the team to add a separate range to show resistance here soon.
