Honeywell 621-9937 Description Description Honeywell Parallel I/O Module (8/16/32 Point Related products HONEYWELL 621-9937 HONEYWELL 620-3590 HONEYWELL DM106-0-A-00-0-R-1-00000-000-E0 HONEYWELL AX51-061-001 HONEYWELL 51304156-100 HONEYWELL 621-0009