61C is the general series code for Reliance AutoMax rack I/O modules; numeric 544 stands for fixed specification of 16-channel RTD thermal resistance dedicated input without universal voltage/current input function. Base model 61C-544 has no revision suffix, upgraded variant 61C-544A optimizes constant-current drive circuit and open-circuit diagnosis logic, fully pin-to-pin interchangeable with base version on same rack backplane.

Supports standard 3-wire Pt100 RTD sensor as primary input, optional configuration for partial 2-wire RTD via system software parameter setup; total 16 independent measuring channels, each channel equipped independent constant-current excitation source. Standard measuring range: -200℃ ~ +850℃, built-in 12-bit A/D conversion chip, full-scale measuring accuracy ≤±0.25%FS, internal hardware open-circuit detection for broken RTD wiring fault alert. Module draws all operating power from rack backplane bus with no external auxiliary power needed. Continuous working ambient temperature: -20℃ ~ +55℃, storage temperature: -40℃ ~ +85℃, applicable humidity 5%~95% non-condensing, compliant with UL and CE industrial certification and unified DIN rack installation dimension of full 61C lineup. Internal signal isolation withstand voltage reaches 2000VAC between field side and backplane bus side.

Rear side adopts proprietary gold-plated dedicated backplane connector to plug into AutoMax system rack backplane, transmits converted temperature digital data to main CPU through exclusive manufacturer internal bus protocol. Front panel installs detachable screw terminal block for field RTD sensor wiring, compatible with external terminal adapter for centralized long-distance wiring expansion. One global power/communication status LED equipped on front panel, no independent per-channel indicator lamps configured; no external RS485 or Modbus communication port, all data interaction depends entirely on rack internal backplane bus transmission.

Provide stable constant-current excitation for field-installed Pt100 RTD thermal resistance sensors, convert resistance variation induced by temperature change into analog electrical signal, filter field high-frequency interference via onboard low-pass filter circuit, realize A/D digital conversion and cyclic upload temperature numerical value to upper AutoMax PLC controller through backplane bus. Automatically trigger fault flag and feed abnormal code to control system when RTD wire open/short circuit occurs, supporting mixed installation with other analog input/output and digital I/O modules of 61C series inside identical control rack to build distributed multi-point temperature acquisition layout.

Mainly used for furnace body temperature monitoring of metallurgical heating furnace, reactor and pipeline temperature collection in chemical production line, drying roller temperature detection of papermaking machinery, boiler and heat exchanger multi-point temperature measurement in thermal power industry; widely adopted as spare replacement component for obsolete production line control cabinet upgrading project with massive distributed temperature measuring points.

Cut off overall rack power and wait over 15 minutes for internal capacitance residual power discharge before module disassembly, replacement or field terminal rewiring work. Complete semi-annual routine maintenance: tighten terminal fastening screws, blow away internal accumulated dust with dry low-pressure compressed air, check terminal pin corrosion and oxidation status. When measured temperature data drifts abnormally or module indicator flickers, firstly verify field RTD sensor wiring and resistance parameter to eliminate peripheral circuit failure before module replacement. Avoid overloading input terminals with external high voltage to prevent damage of internal constant-current drive and A/D conversion circuit components; annual full-channel precision calibration is required for long-term continuous running modules to guarantee temperature measuring precision.