S7-400H sync module V4 — what changed
The Siemens 6ES7960-1AA04-0XA0 is the V4 synchronization module for the S7-400H redundant system, explicitly marked as a replacement part for the earlier V3 variant. It supports patch cable lengths up to 10 m between the two CPUs. Maximum current consumption is 210 mA from the backplane bus — a number to check against the rack power budget if the slot is far from the power supply.
Integration into S7-400H
This module connects the two CPUs of a redundant H system via a patch cable up to 10 m. The V4 designation replaces the V3 variant (6ES7960-1AA03-0XA0) with backward compatibility in the same slot and cable interface. The 1.1 W power loss is low enough that no forced-air cooling is required in a typical IP20 cabinet, but the 210 mA backplane draw should be summed with other modules in the rack to stay within the power supply's rated output.