1766-RM001A-EN-P MicroLogix 1400 Programmable Controllers ...

114 Using the High-Speed Counter and Programmable Limit SwitchOverflow Mask (OFM)Description Address Data Format HSC Modes (1) Type User Program AccessOFM - Overflow HSC:0/OFM bit 0…9 control read/writeMask(1) For Mode descriptions, see HSC Mode (MOD) on page 116.The OFM (Overflow Mask) control bit is used to enable (allow) or disable(not allow) an overflow interrupt from occurring. If this bit is clear (0),and an overflow reached condition is detected by the HSC, the HSC userinterrupt is not executed.This bit is controlled by the user program and retains its value through apower cycle. It is up to the user program to set and clear this bit.Overflow Interrupt (OFI)Description Address Data Format HSC Modes (1) Type User Program AccessOFI - Overflow HSC:0/OFI bit 0…9 status read/writeInterrupt(1) For Mode descriptions, see HSC Mode (MOD) on page 116.The OFI (Overflow Interrupt) status bit is set (1) when the HSCaccumulator counts through the overflow value and the HSC interrupt istriggered. This bit can be used in the control program to identify that theoverflow variable caused the HSC interrupt. If the control program needsto perform any specific control action based on the overflow, this bit isused as conditional logic.This bit can be cleared (0) by the control program and is also cleared bythe HSC sub-system whenever these conditions are detected:• Low Preset Interrupt executes• High Preset Interrupt executes• Underflow Interrupt executes• Controller enters an executing modePublication 1766-RM001A-EN-P - October 2008