A controls team needed two Trane SC controllers exposed over Modbus TCP to a downstream PLC. Chipkin QuickServer helped convert the BACnet/IP points into a usable register map and corrected a multi-device mapping error during the live installation window instead of forcing a delayed return visit.
This case is useful because it shows a common multi-device integration failure mode. The gateway path was correct, but the first point map duplicated values across both upstream controllers, which would have doubled the downstream Modbus footprint and confused the PLC-side logic.
At a Glance
- Industry: HVAC / building automation controls
- Customer: Commercial controls integrator
- Facility type: Controller-to-PLC integration project
- Client role: Field controls technician and service manager
- Project scale: 2 Trane SC controllers and 11 final mapped points
- Protocols: From: BACnet/IP -> To: Modbus TCP
- Chipkin product: Chipkin QuickServer FS-QS-2010
- Project start: September 2022
- Internal reference: FSE15114
Architecture: Trane SC-1 and SC-2 controllers -> BACnet/IP -> Chipkin QuickServer -> Modbus TCP PLC
BACnet/IP to Modbus TCP Challenge
The upstream/server side was a pair of Trane SC controllers serving data over BACnet/IP. The downstream/client side was a GE PLC that needed the same information presented as Modbus TCP registers.
The project depended on getting the point ownership right across both BACnet devices. Five points belonged to one controller and six to the other, but the initial configuration treated all eleven points as if they belonged to both devices. That would have produced twenty-two downstream registers instead of the intended eleven.
The public value here is straightforward: the field technician found the issue during installation, Chipkin corrected it immediately, and the site did not have to lose the commissioning window to a point-map cleanup that could be fixed the same day.
Why Chipkin
This was a strong fit for Chipkin because the problem was not generic protocol conversion. It was multi-device point ownership, BACnet instance handling, and downstream Modbus mapping under live commissioning pressure. Chipkin QuickServer provided the gateway path, and Chipkin support delivered the corrected map fast enough to keep the installation moving.
That matters in PLC handoff projects because a small mapping error can ripple into every downstream register assumption.
The Solution
Chipkin configured the QuickServer to read from two Trane SC BACnet/IP devices and serve the result as a single Modbus TCP endpoint for the PLC. The customer supplied the two BACnet device instances, and the final intended scope was eleven points total: five from SC-1 and six from SC-2.
When the field install exposed the duplication error, Chipkin corrected the configuration the same day and re-issued the file during a live support call. That narrowed the problem to the actual device-to-point split rather than forcing the customer to debug Modbus behavior or BACnet connectivity that was never the real blocker.
The result was a cleaner PLC-facing register model and a faster recovery during installation.
For another project where Chipkin kept a live controls commissioning window on track, see the EtherNet/IP to BACnet/IP PLC Alarm Integration case study.
Trane Controller Integration Results
The project delivered a working BACnet/IP to Modbus TCP handoff for a two-controller deployment.
Project proof points:
- 2 Trane SC controllers were mapped into one QuickServer integration.
- 11 final points were exposed after the per-device split was corrected.
- The register duplication error was fixed the same day it was discovered during installation.
- The field visit stayed productive because the corrected file was delivered during the commissioning window.
The technician’s response captured the turnaround:
“Awesome thank you! I will let you know if I need any help, hoping to get this set up next week.”
— Controls technician, commercial HVAC integrator
Have a Similar BACnet-to-Modbus Project?
Need to expose BACnet/IP controller data to a Modbus TCP PLC without losing time to point-map errors during installation? Chipkin can help with QuickServer configuration, per-device mapping, and fast commissioning support. Tell us about your project.
Frequently Asked Questions
Can QuickServer expose Trane SC controller data to Modbus TCP?
Yes. In this deployment, QuickServer read the two Trane SC controllers over BACnet/IP and exposed the final point set to the PLC over Modbus TCP.
Can multiple BACnet/IP devices be combined into one Modbus TCP handoff?
Yes, but the point ownership has to be modeled correctly. This case study shows why a two-device mapping can fail if the gateway treats every point as if it belongs to both upstream devices.
Can Chipkin fix a point-map error during commissioning?
Yes. The project recovered because Chipkin corrected the duplication issue during the live installation window instead of forcing the customer to wait for a later return visit.