What is Main Control Output
The main control output is the core output of the temperature controller, used to directly control the load. Its purpose is to stabilize the temperature at the set value, and it belongs to the closed-loop control execution terminal.
Common types
Relay contact output (passive dry contact, for controlling contactors and fans)
SSR drive output (for driving solid state relays)
Thyristor trigger output
Analog regulating output: 0-10V / 4-20mA
Main features
Directly control heating, cooling and actuator equipment
Realize PID automatic regulation according to temperature deviation
Target loads: contactors, solid state relays, power regulators
Belongs to control output, responsible for on-site temperature regulation
What is Transmission Output
Transmission output, also called analog retransmission output, converts the actual measured temperature into standard industrial analog signals for remote transmission.
Common signal types
4-20mA / 0-20mA / 0-10V / 0-5V
Main features
Used for temperature data uploading and remote monitoring
Output signal changes linearly with actual temperature
Connected to PLC, HMI, recorder, data acquisition module and host computer
Belongs to signal transmission output, only for data collection, not participating in on-site control
Comparison: Main Control Output vs Transmission Output
表格
| Item | Main Control Output | Transmission Output |
|---|---|---|
| Function | Control load and regulate temperature | Remote temperature signal transmission & data collection |
| Working logic | PID adjustment / on-off control | Linear follow actual temperature |
| Connected device | Contactor, SSR, power regulator | PLC, HMI, recorder, upper computer |
| Signal type | Relay contact / SSR pulse / analog regulation | Standard 4-20mA / 0-10V analog signal |
| Control participation | Directly involved in temperature closed-loop control | Only data transmission, no control function |
| Application | On-site local temperature control | Centralized monitoring and remote acquisition |
Application Scenarios
Only Main Control OutputIndependent ovens, electric furnaces and standalone heating equipment; only local constant temperature control is required, no data upload needed.
Only Transmission OutputNo direct load control on site; temperature signal is sent to PLC or upper computer for unified system logic control.
Dual Output Used Together (Most Common)
Main control output: Realize precise local constant temperature by controlling heating/cooling loads
Transmission output: Transmit real-time temperature to PLC, touch screen and recorder for remote viewing, data recording and system interlock
Selection & Wiring Notes
If you need to control heating loads, choose a model with main control output.
If temperature data needs to be uploaded to PLC or host computer, please select transmission output.
Transmission output is active analog signal; please pay attention to positive / negative polarity and use shielded cable for long distance.
Relay main control output is passive dry contact, no polarity requirement, external power supply is needed to form a loop.
Do not mix the two outputs; wrong connection may damage the instrument port.
Summary
Main Control Output - Controls the load and keeps temperature stable locally.
Transmission Output - Transmits real-time temperature signal remotely for monitoring and data recording.
Reasonable matching of both outputs realizes precise local temperature control as well as remote monitoring and automatic system linkage.