Error Code Slow beeping

Exit delay warning is active (if programmed) or entry delay warning is active, indicating time to exit or disarm the system.

? What Causes This

System is in exit delay or entry delay period.

✓ How to Fix It

Exit through the designated entry/exit door during exit delay. If in entry delay, disarm the system with your security code before the entry delay expires to avoid an alarm.

Source: page 50 of the official manual

From the manual

Manual page 50 — Honeywell error Slow beeping

This error code appears in:

Honeywell Vista-20P Security System