Honeywell ALERTON ACM-VLX Installation And Operation Manual page 61

© Honeywell. All Rights Reserved. LT-VLXEXPAXMIOG Rev. 01
Installation and Operations Guide
BOs
The present-value of a BO is either ON (ACTIVE) or OFF (INACTIVE) as a
result of the priority array.
The H-O-A switch overrides all software commands when set to
H-O-A switch
HAND or OFF.
See "Appendix G: H-O-A and trimpot status values" on page 95 for a reference
of AVs associated with H-O-A switch and trimpot status.
Priority-array index 4 reflects H-O-A status:
• INACTIVE = Switch in OFF position
• ACTIVE = Switch in HAND position (ON)
• NULL = Switch is in AUTO position
The H-O-A switch overrides all software commands, regardless
IMPOR TA N T
of the command's priority for writing. If a command is written at priority-array
index 1, 2, or 3, and the H-O-A switch is in HAND or OFF mode, the present-
value may not accurately reflect the actual status of the output.
Anti-cycle properties
minimum-off-time — enable you to set anti-cycle limits for a BO in seconds.
This is carried out through priority-array index 6. For example, by writing a
value of 60 to the minimum-on-time property of a BO, you set a minimum ON
time of 60 seconds. If DDC writes an ACTIVE (ON) command (at priority-array
index 9), priority-array index 6 is automatically set ON and remains ON for 60
seconds after the command is issued. Present-value commands written with a
priority lower than 6 will be ineffective until the time expires and priority-array
index 6 returns to NULL. By default, minimum-on-time and minimum-off-time
are set to 0.
Software anti-cycle measures are not meant to replace hard-wired
WAR NING
safety interlocks.
AOs
AO present-values provide a control signal from 0–100 that drives the
corresponding output from either 0–20mA or 0–10VDC as configured with the
output DIP switch on the EXP/AXM. If necessary, scale the AO in DDC for the
desired output range (for example, scale 20-100 for a 4-20mA range).
H-O-A switch and trimpot
H-O-A trimpot drives the output from 0–100% (0–20mA or 0–10VDC as
appropriate). When the switch is in OFF position, the output is at 0%. The
trimpot value covers the full range of the output, regardless of any software
scaling.
See "Appendix G: H-O-A and trimpot status values" on page 95 for a reference
of AVs associated with H-O-A switch and trimpot status.
|
VLX/ACM-VLX data, DDC, and automation
Two properties of a BO object — minimum-on-time and
When the H-O-A switch is in HAND position, the
61