Set Filter - 0X66 - Honeywell CM4 Technical Handbook

CM4 Four-Point Continuous Monitor

Set Filter - 0x66

This command allows a master to set the lifetime of a filter. See packet
44 for a discussion of these parameters. The valid range of lifetimes is
30 to 365 days. The system maintains the number of days remaining
as a constant if the lifetime changes.
Command packet to instrument:
Command code (0x66) - 1 byte
Internal filter lifetime (days) - 2 bytes
External filter lifetimes (days) - 2 bytes
Response from instrument:
Command code (0x66) - 1 byte
CM4 date - 2 bytes
CM4 time - 2 bytes
Status - 1 byte
0x00 = packet accepted
0x01 = internal filter lifetime unacceptable
0x02 = external filter lifetime unacceptable
0xFF = slave in monitor, unable to accept changes
CM4 Technical Manual
Get Duty Cycle - 0x69
This command allows the master to find out the minimum window time
and the monitor relay action during duty cycle bits on a slave.
The minimum window time (or duty cycle) defaults to zero seconds.
But it may be set larger to conserve tape in installations that have
some concentration of gas for long periods of time. The tape will not
advance until the minimum window time has accumulated even if
the tape is saturated. During periods when the tape is saturated but
prevented from advancing, the CM4 will continue to report the most
recent concentration reading. Unfortunately it will not be able to detect
any changes in concentration during this period because the tape is
saturated.
By default, the monitor relay (RY6) will energize when monitoring
is temporarily suspended because of tape saturation. However this
reaction can be inhibited for individual points. The "monitor relay action
during duty cycle" bits default to TRUE but can be set to FALSE via
either the keypad or serial packet 0x65, Set Duty Cycle.
Command Packet to slave:
Command code (0x69) - 1 byte
Response from slave:
Command code (0x69) - 1 byte
CM4 date 2 bytes
CM4 time 2 bytes
Bits permitting monitor relay action during Duty cycle - 1 byte
bit 0 point1
bit 1 point2
bit 2 point3
bit 3 point4
bits 4-7 unused (always 0)
Min window time (seconds) - 2 byte
Status - 1 byte (always 0x00)
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