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Technical Bulletin—TC-9100 Universal Controller
The TC-9100 Universal Controller has a low limit module with a
numerical input connection, a set point parameter, and a low limit
differential parameter. The output of the module is set to 1 when the
value of the input goes below the set point, and returns to 0 when the
value of the input goes above the set point plus the value of the low limit
differential. The output may be read by a supervisory system at Item
LSC, Bit 6 (AFM), and the output of a programmable module configured
as a Controller Algorithm can be forced to 100% when a Low Limit
condition exists. This module is normally used for low temperature
protection (anti-freeze), where the input is connected to an analog input
or external analog input measuring room temperature or outdoor air
temperature, and controller modules controlling perimeter heating are
enabled for Low Limit module override. The Low Limit override has the
highest priority in a control module and will override all other overrides,
including the OFF mode override. Refer to
Controller Algorithms 1 to 6 –
General
under
Programmable Module Configuration
for further details.
FDIF
FSP
0
1
Output
(AFM)
Input
Figure 14: Low Limit Module Function
The configuration parameters to be defined for the low limit module are
listed below. Refer to
Appendix 2 – Worksheet 3
, or
Appendix 1 – Table
1: Item List
, for the Item addresses.
Table 18: Low Limit (Anti-freeze) Module Configuration Items
Item Tag Type
Description
FT@ Connection
Source
of the input value for the low limit module.
FSP Number
Set Point
value of the low limit module.
FDIF Number
Low Limit Differential
The parameter that is dynamically generated by the controller from the
configuration parameters is shown below:
Table 19: Low Limit (Anti-freeze) Module Dynamic Items
Item Tag Item Address
(Hex/Dec)
Description
AFM
26/38, Bit 6
Low Limit Module Output (Anti-freeze Mode)
Low Limit
(Anti-freeze)
Module
Configuration
Configuration
Parameters
Dynamic
Parameters
