Thomas said the German technology conglomerate forecasts revenue at the division to be a good 10% below the previous year's levels.
Margins for the division are seen at 17% in the second quarter, rather than the 20% previously expected.
Thomas's comments on sales and margins were described by Redburn Atlantic analyst James Moore as concerning.
Shares were trading down 5.35% at 1323 GMT, at the bottom of the pan-European index.
Two traders also pointed to cautious comments on China from Thomas, who sees a more difficult environment than expected in China in factory automation.
"The destocking will take longer than expected, probably until the end of the year," Thomas said, according to a recording of the event.
(Reporting by Alexander Hübner, writing by Paolo Laudani and Tristan Veyet, Editing by Louise Heavens)