AMX VST Instruction Manual page 24

ViewStat Programming Protocol
Thermostat Action Commands (Cont.)
Command
DIF1, DIF2, & OFFSET
Temperature Control Configura-
tion Settings
SHUM
Humidify Control Setting
20
Description
Three temperature control variables can be accessed through the View-
Stat command set; they are first stage differential (DIF1), second stage
differential (DIF2) and display temperature offset or bias (OFFSET).
The ViewStat is an on/off type temperature controller. This means that at
some temperature below or above the temperature setting the equipment
is turned on, generating or extracting heat at 100% capacity, and at some
temperature the equipment is turned off. Differential refers to the deviation
from setting that the temperature is allowed to be before the control out-
puts are turned on or off.
The default differential setting is 0.5° F or C for both DIF1 and DIF2. Dif-
ferential settings for each stage can be increased in increments of 0.5°F or
C up to 2°F or C. The SN1 DIF1 command is used to add to the default
differential of 0.5° in increments of 0.5°. For example, SN1 DIF1=1 sets
the first stage differential at 1°F or C (= 0.5° + 1*0.5°), while SN1 DIF1=3
sets the first stage differential at 2° F or C (= 0.5° + 3*0.5°) and SN1
DIF1=0 returns the differential to 0.5° F or C. Second stage differential
setting is the value above or below the first stage differential setting that
the temperature is allowed to deviate before turning on the second stage of
either heating or cooling. For example, setting SN1 DIF1=0 and SN1
DIF2=2 will result in first stage operation at temperatures above or below
0.5° while second stage will be activated at 0.5° + 1.5° = 2° above or below
the setting.
Thermostats are factory set to be accurate to within 1° between 60°F and
80°F. Temperature comfort however can be a relative condition, so the
ViewStat allows the temperature displayed on the thermostat to be artifi-
cially offset. OFFSET is used to offset the display temperature. For
example setting SN1 OFFSET=-3 will change a displayed temperature
reading of 72°F to be 69°F.
Syntax:
SN[address] DIF1=Integer between 0 and 3 inclusive
Reply Format:
SN[address] DIF1=Integer between 0 and 3 inclusive
Syntax:
SN[address] DIF2 =Integer between 0 and 3 inclusive
Reply Format:
SN[address] DIF2 =Integer between 0 and 3 inclusive
Syntax:
SN[address] OFFSET=Integer between -3 through +3
Reply Format:
SN[address] OFFSET=Integer between -3 through +3
Connecting an optional support module configured for humidity control to
the ViewStat changes it from a temperature controller to a humidity con-
troller. The corresponding modes of operation are Humidify, Dehumidify,
Humidify or Dehumidify and Off. SHUM is used to set the "Humidify" control
setting. The humidify setting is that against which the current room humid-
ity is compared to control the humidify output of the thermostat.
Syntax:
SN[address] SHUM={value}%
• Variable:
{value}: Integer value between 10 and 90
Reply Format:
SN[address] SHUM={value}%
ViewStat Communicating Thermostat - Programming Protocol Reference Guide