This fault means the inverter has lost CAN communication with the battery management system. It shows up as a CAN Fail, CAN COM Fail or battery communication error alarm, sometimes with a No Battery alarm or a red LED on the inverter. Common causes are a loose or wrongly wired communication cable, an unsuitable or unshielded cable, faulty bus termination, poor grounding, outdated inverter software, or a battery that is switched off. First check that the battery is on, that the cable is seated and wired correctly, and that the correct battery model is set on the inverter. If the alarm stays, measure the CAN H and CAN L voltages against ground at the inverter, or run the manufacturer's CAN interface loopback test. If the loopback test passes, the inverter is not the cause and the fault lies elsewhere in the installation; if it fails, the battery interface module must be replaced through service. Restart the inverter and contact the manufacturer if the fault persists.
caused_byc1 drafted · lead Poor connector contact
A loose or badly seated communication cable between inverter and battery can drop the link.
tbl=1.r12 h=f40be2333f68sec=h1 h=475873edd6aasec=h393 h=fa95d55eedefc2 drafted · lead Communication bus wiring or termination fault
A faulty termination on the battery-inverter communication cable is listed as a possible cause.
sec=3 h=09dacb162ccac3 drafted · lead Installation error
Wrong wiring of the battery-inverter communication.
sec=h1 h=475873edd6aasec=3 h=09dacb162ccac4 drafted · lead Unsuitable communication cable proposed
Cable not meeting the manual's requirements, missing cores, or no shielding layer.
tbl=1.r12 h=f40be2333f68sec=3 h=09dacb162ccac5 drafted · lead Inadequate earthing
Incorrect grounding of the inverter or battery system.
sec=3 h=09dacb162ccasec=h76 h=98737cac3bc3c6 drafted · lead Device firmware defect
Inverter software version not up to date.
sec=3 h=09dacb162ccac7 drafted · lead Signal cable electromagnetic interference
Serious interference on the CAN link.
tbl=1.r12 h=f40be2333f68review note: support check: partial - u1 mentions serious interference only as a hardware problem to check; it does not say the interference is on the signal cable.
c8 drafted · lead Battery switched off proposed
Battery not powered on or not switched on correctly.
sec=h393 h=fa95d55eedefsec=h352 h=fa95d55eedefsec=h352 h=fa95d55eedefsec=h76 h=98737cac3bc3c9 drafted · lead Inverter parameter settings
Wrong battery model configured on the inverter.
sec=h5 h=19991408763bsec=h1 h=53cfcd3eb62areview note: support check: partial - u14 says to verify the correct battery model is configured when alarms appear, but it does not state a wrong model as a cause of the fault.
affectsc10 verified · fact Battery energy storage system
sec=h393 h=fa95d55eedefsec=h76 h=98737cac3bc3verified by: review-workflowverified on: 2026-10-24
A defect in the inverter's CAN interface on the battery interface module is one possible cause.
sec=3 h=09dacb162ccasec=h1 h=b20d3ee6952ac12 drafted · lead Communication cable proposed
sec=h1 h=475873edd6aasec=h76 h=98737cac3bc3presents_asc13 drafted · lead Communication loss
CAN communication between inverter and battery is lost.
tbl=1.r12 h=f40be2333f68sec=h393 h=fa95d55eedefsec=h352 h=fa95d55eedefsec=h352 h=fa95d55eedefsec=h76 h=98737cac3bc3c14 drafted · lead Battery not detected by inverter
The CAN interface does not detect the connected batteries or backup box; a No Battery alarm may appear.
sec=h5 h=19991408763bsec=3 h=09dacb162ccasec=h1 h=b20d3ee6952adetected_byc15 drafted · lead Battery CAN interface functional test
Loopback test with a test cable; success rate 100 means the inverter's CAN inputs work and the fault lies elsewhere.
sec=7 h=edeb28b371f9sec=3 h=09dacb162ccasec=h1 h=b20d3ee6952ac16 drafted · lead Communication bus voltage test
Multimeter check of CAN H and CAN L against ground on the inverter side.
sec=h1 h=5ebb90784532sec=h1 h=53cfcd3eb62ac17 drafted · lead Communication test proposed
sec=h76 h=98737cac3bc3review note: support check: partial - u33 says to perform a communication test via the user interface as a corrective measure, but it does not clearly state this as detecting the fault.
c18 verified · fact Inverter display check
tbl=62 h=60eac848d32btbl=62.r6 h=af1b9f4fd00averified by: review-workflowverified on: 2026-10-24
mitigated_byc19 drafted · lead Communication cable check
tbl=1.r12 h=f40be2333f68sec=h1 h=475873edd6aasec=h393 h=fa95d55eedefsec=h76 h=98737cac3bc3c20 drafted · lead Battery connection check
sec=h4 h=4634327bc280sec=h1 h=53cfcd3eb62asec=h393 h=fa95d55eedefc21 drafted · lead Battery parameter check proposed
Confirm the correct battery model and communication pins are configured.
sec=h5 h=19991408763bsec=h1 h=53cfcd3eb62areview note: support check: partial - u14 gives the model and pin check, but it only partly covers 'communication pins configured'.
c22 drafted · lead Communication bus termination and cabling practice
Use at least Cat 5e twisted pair, respect maximum length, strip properly, use shielded cabling.
sec=h76 h=98737cac3bc3sec=h11 h=ee2da61a2b27c23 drafted · lead Grounding conductor check
sec=h76 h=98737cac3bc3sec=h11 h=ee2da61a2b27c24 drafted · lead Firmware update
sec=h1 h=b20d3ee6952asec=h11 h=ee2da61a2b27review note: support check: partial - u24 lists firmware compatibility among the checks and u35 says to update firmware if necessary, but neither says an update resolves the fault.; review: partial - SMA says to check the firmware and update it if needed as part of the CAN test, and Solis lists firmware compatibility among the checks, but neither passage says a firmware update fixes the BMS communication fault.
c25 drafted · lead Inverter restart
tbl=1.r12 h=f40be2333f68c26 drafted · lead Battery interface module replacement proposed
Needed when the CAN functional test shows success rate 0.
sec=h1 h=b20d3ee6952ac27 drafted · lead Contact manufacturer service
tbl=1.r12 h=f40be2333f68sec=h76 h=98737cac3bc3