Honeywell ALERTON ACM-VLX

To Next Page

To Previous Page

Installation and Operations Guide

VLX/ACM-VLX data, DDC, and automation

BOs

The present-value of a BO is either ON (ACTIVE) or OFF (INACTIVE) as a

result of the priority array.

H-O-A switch The H-O-A switch overrides all software commands when set to

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

IMPORTANT The H-O-A switch overrides all software commands, regardless

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 Two properties of a BO object — minimum-on-time and

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.

WARNING Software anti-cycle measures are not meant to replace hard-wired

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 When the H-O-A switch is in HAND position, the

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.

Honeywell ALERTON ACM-VLX - BOs; AOs