Overview
A group of devices on the RS485 bus stops reporting at the same time while the rest of the bus continues to function. The affected devices are usually clustered physically · for example, all devices on one row of the panel, or every device in a second panel sharing the controller · even though their Modbus IDs may not be sequential. This pattern almost always points to a physical break in the RS485 daisy chain.
How this issue is diagnosed
This fault is resolved jointly between the installer on site and Hybird support. The installer reports the symptoms and walks the panel to locate the break; Hybird support reads the controller logs from Hybird Admin to identify which devices have dropped off and helps map the affected Modbus IDs onto the physical chain. If the symptoms in the next section match what you are seeing, contact Hybird support at support@hybird.energy or +45 3020 4900 to begin the joint diagnosis.
Symptom
Multiple devices stop reporting simultaneously, with devices upstream of the break (closer to the controller in the chain) continuing to report normally.
Affected devices share a physical location (a region of one panel, or an entire secondary panel) rather than a numerical range of Modbus IDs.
From the support side, controller logs in Hybird Admin show Modbus timeout errors on each affected ID. Each non-reporting device produces a log line in the form: [<timestamp>] [ERROR] [GET_MEASUREMENTS] Failed to read measurement from Device <modbus_id> (<device_type>): Modbus error: Modbus query timed out. Devices upstream of the break produce no error and continue to report normally. Log format may change over time as the underlying libraries are updated, so search by symptom rather than by exact string.
Possible causes
Loose or disconnected RS485 wire at one point in the daisy chain. Every device downstream of that break loses communication. This is the most common cause when a contiguous group of devices drops off.
Broken or damaged RS485 cable between two devices, particularly at panel-to-panel transitions where the cable is more exposed.
Multiple coincident reverse-polarity faults on the affected devices. Less likely, but produces a visually similar pattern. See Single breaker not reporting · troubleshooting guide and No devices reporting · troubleshooting guide.
Diagnosis
Hybird support will list every device that has stopped reporting and identify the affected Modbus IDs from the controller logs. The Modbus IDs do not need to be sequential · the daisy chain is wired in whatever order the panel layout allows, and may include external meters at address 120 or higher. The diagnostic question is whether the affected devices share a physical region rather than a numerical range.
Once the support-side list of affected Modbus IDs is known, the installer maps it onto the physical chain on site:
Identify which physical devices in the panel correspond to the affected Modbus IDs. Pay particular attention to whether the affected devices are clustered in one area, on one row, or in one of multiple panels sharing the controller.
Identify the last device that is reporting in the chain. The break is between that device and the first non-reporting device downstream.
Inspect the RS485 wiring between the last reporting device and the first non-reporting device. Look for a disconnected, loose, or damaged conductor. Pay particular attention to any cable run that crosses between two panels.
For a fuller checklist of what to inspect on site, see On-site visual checks · what to inspect on a Hybird panel.
RS485 is low-voltage signal wiring and can be worked on with the panel live. Do not de-energise the panel · the installation is likely powering active loads. Apply standard panel-work precautions: avoid contact with AC terminals, and follow local regulations (Stærkstrømsbekendtgørelsen in Denmark, BS 7671 in the UK, VDE 0100 in Germany) for working inside a live distribution panel.
Resolution
Reconnect or replace the broken section of the RS485 daisy chain on site. The panel can remain energised.
Confirm both A and B conductors are seated and secure at every termination in the affected segment. The RS485 plug is push-in and hand-tightened; no torque value applies.
Hybird support will confirm from Hybird Admin that every previously affected device returns to active status.
Prevention
Where the daisy chain crosses between panels, use screened twisted pair for runs longer than approximately 30 m, with the screen connected to controller GND and 120 Ω termination at each end. Practical reach depends on cable quality, routing, and EMI; for runs over approximately 500 m a repeater is required.
Avoid star or T-tap topologies. The bus must be a single daisy chain only.
Route panel-to-panel cabling so that it is protected from mechanical damage and not pulled through tight bends.
After commissioning, confirm with Hybird support that every device is online before closing panels and leaving site.
When to escalate
If the daisy chain has been confirmed intact end-to-end and a group of devices still does not report, contact Hybird support at support@hybird.energy or +45 3020 4900. Coincident multi-device failures are unusual and may indicate a hardware issue with the affected devices or the controller's RS485 port.
Summary
When a physically clustered group of devices drops off the bus simultaneously, the cause is almost always a break in the RS485 daisy chain between the last reporting device and the first non-reporting device. Confirm the affected devices share a physical region rather than a numerical Modbus range, then inspect the chain between them.