Honeywell 621-9940 Description Description Honeywell Serial I/O Module (8/16/32 Point) Related products HONEYWELL STD924-A1A-00000-MB.3H+XXXX HONEYWELL 621-9937 HONEYWELL 621-9934 HONEYWELL 620-0090 HONEYWELL C7027A1031 HONEYWELL 620-0041