Code 26286: [Channel %1: ] Axis %2 risk of collision preactivated protection zones interface signal(s) %3
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Axis %2 risk of collision preactivated protection zones interface signal(s) %3 alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Parameters: %1 = Channel number %2 = Axis name, spindle number %3 = Interface signal(s) Definitions: A collision was detected involving at least one preactivated protection zone. Such a collision can occur if the interface si gnal assigned to a preactivated protection zone has been activated. That is if a preactivated protec tion zone has become an active protection zone. Either a preactivated and a (static) active protection zone can be involv ed in the collision, or two preactivated protection zones can be involved. The number(s) of the interface signals assigned to the preactivated protection zones involved are output in the alarm text. Reaction: NC Start disable in this channel. Interface signals are set. Alarm display. Alarm reaction in Automatic mode. NC Stop on alarm. Remedy: Reset activating interface signals. Redefine protection zones. Retract Program Continuation: Clear alarm with NC ST ART or RESET key and continue the program.
Source: SINUMERIK 840D sl / 840Di sl / SINAMICS S120 Diagnostics Manual (DAsl, 03/2009)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Siemens SINUMERIK 840D CNC Alarms
Siemens controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 26286 on the SINUMERIK 840D CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Siemens's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4014 Siemens SINUMERIK 840D CNC codes.
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