51304797-100 Honeywell Central control module Brand new

Function

The LLMUX IOP module supports up to 64 channels of temperature inputs. Low level inputs use the Honeywell PMIO 

LLMUX FTA. Each FTA supports 16 channels. Two types of LLMUX FTA are supported. One provides 16 RTD inputs. 

The other provides 16 TC or MV inputs. Any combination of FTAs may be used to provide the mix of TC, mV or RTD 

points required.

Notable Features

• TC and RTD operation

• Remote cold junction capability

• 1 Second PV scanning with OTD protection

• Configurable OTD protection (See below)

• Temperature points can be added in 16 point 

increments

Temperature Support

The Temperature Input LLMUX supports the existing solid state PMIO LLMUX FTA. The PMIO LLMUX FTA supports 

RTD and Thermocouple (TC) inputs. The Temperature variable is collected from all points at a 1 second rate. The 1 

second update includes a configurable check for Open Thermocouple Detection (OTD) (see below) before propagation 

of the temperature variable. All TC inputs are compensated using a Cold Junction Compensation (CJT) device.

Sampling and Open Sensor Detect

The Temperature multiplexer supports RTD and Thermocouples with Open Sensor Detect before PV delivered if so 

configured. With the OTD configuration active, the PV is sampled and held while an OTD cycle is performed within the 

same measurement window. If the OTD is negative, the PV is propagated up through the system. If the OTD is positive, 

the PV is set to NAN and the input channel soft failure is set. In this way, no inappropriate control action occurs for PV 

values that are invalid due to an open thermocouple. PV sampling/reporting incurs no added delays from OTD 

processing