![\"Therm](\"http:\/\/protofusion.org\/wordpress\/wp-content\/uploads\/2016\/03\/therm_rtd_full-600x400.jpg\")
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Therm RTD is an addition to the Therm PID Controller<\/a> family, with support for RTD temperature sensors. RTDs (or Resistance Temperature Detectors) use a coil of fine wire made from\u00a0a material (usually platinum, copper or nickel) that has a very\u00a0predictable temperature coefficient of resistance (or change in resistance as temperature changes). RTDs\u00a0are generally\u00a0more accurate and stable than\u00a0thermocouples, and\u00a0have a much greater range than thermistors\u00a0–\u00a0although they can tend to be more expensive than both.<\/p>\n The hardware and functionality of Therm RTD is very similar to the original Therm; the biggest change is the replacement of the thermocouple chip with a MAX31865 chip to support RTDs instead. This chip also supports thermistors; however, the reference resistor must be replaced with a larger one before using higher resistance thermistors. The OLED display, USB port, and solid state-relay driver are left unchanged, but the external power input has been removed. Removable mounting feet have also been added to assist in installation.<\/p>\n Therm RTD PCB<\/p><\/div>\n The new hardware comes with a firmware update that is compatible with both models. The menu system has been improved, with more extensive reboot and reset options. Issues with non-volatile memory have been fixed, allowing settings to be saved across reboots. Temperature display resolution has been increased for both C and F, and PID calculations are now performed using 1\/10th\u00a0degree precision. Source code for both the firmware and\u00a0the hardware\u00a0are available on the Protofusion repository<\/a>.<\/p>\n Future updates\u00a0are planned to add software-selectable reference resistors so that both RTDs and thermistors can be used without hardware modifications. Temperature profiles with support for multiple setpoints are\u00a0also in the works\u00a0to facilitate more complex temperature control applications.<\/p>\n","protected":false},"excerpt":{"rendered":" Therm RTD is an addition to the Therm PID Controller family, with support for RTD temperature sensors. RTDs (or Resistance Temperature Detectors) use a coil of fine wire made from\u00a0a material (usually platinum, copper or nickel) that has a very\u00a0predictable…<\/span><\/p>\n![\"Therm](\"http:\/\/protofusion.org\/wordpress\/wp-content\/uploads\/2016\/03\/therm_rtd_pcb-300x200.jpg\")