Application Solution for Heat Exchange Stations Based on Tengcon XT-912 PLC — System Block Diagram
Author: From: Add Time: 2026-10-15 15:38:40
I. System Block Diagram
┌─────────────────────────────────────────────────────────────────────────────┐
│ Dispatch Platform Layer │
│ ┌───────────────────────────────────────────────────────────────────────┐ │
│ │ Heating Dispatch Center SCADA (IFIX / INTOUCH / KingView / ForceControl) │
│ │ Functions: Real-time monitoring · Alarm management · Historical │ │
│ │ curves · Energy consumption analysis · Remote dispatching │ │
│ └───────────────────────────────────────────────────────────────────────┘ │
└─────────────────────────────────────────────────────────────────────────────┘
▲
│ Modbus TCP / MQTT / Tengcon IoT Protocol
│ (3G/4G router · ADSL · Community broadband · Fiber)
│
┌─────────────────────────────────────────────────────────────────────────────┐
│ XT-912 Control Layer (Inside Station Control Cabinet) │
│ │
│ ┌─────────────────────────────────────────────────────────────────────┐ │
│ │ Tengcon XT-912 Wide-Temperature Ethernet PLC │ │
│ │ ┌──────────┐ ┌──────────┐ ┌──────────┐ ┌──────────────────┐ │ │
│ │ │ 16 AI │ │ 4 AO │ │ 8 DI │ │ 6 DO │ │ │
│ │ │ 24-bit │ │ 16-bit │ │ Optically│ │ Transistor │ │ │
│ │ │ A/D │ │ D/A │ │ isolated │ │ 0.5 A/channel │ │ │
│ │ └──────────┘ └──────────┘ └──────────┘ └──────────────────┘ │ │
│ │ ┌──────────────────────┐ ┌──────────────────────────────────┐ │ │
│ │ │ 2×RS232/RS485 │ │ 1×10M/100M Ethernet port │ │ │
│ │ │ 2×RS485 │ │ Supports Modbus TCP / MQTT │ │ │
│ │ │ Supports Modbus / │ │ Supports Tengcon IoT protocol │ │ │
│ │ │ Freeport programming │ │ │ │ │
│ │ └──────────────────────┘ └──────────────────────────────────┘ │ │
│ │ Programming: IEC61131-3 standard Power: AC90~264V Power: <12W │ │
│ │ Operating temp: -40℃~85℃ Protection: IP20 Size: 169×134×63mm │ │
│ └─────────────────────────────────────────────────────────────────────┘ │
│ │
│ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ │
│ │ Local HMI │ │ Heat meter / │ │ VFD │ │ Electric │ │
│ │ (RS232/485) │ │ Flow meter │ │ Circulating │ │ control valve│ │
│ │ │ │ (RS485) │ │ pump / Makeup │ │ Primary shut-│ │
│ │ │ │ │ │ water pump │ │ off valve │ │
│ └──────────────┘ └──────────────┘ └──────────────┘ └──────────────┘ │
└─────────────────────────────────────────────────────────────────────────────┘
▲
│ 4-20mA / 0-10V / Dry contact / RS485
│
┌─────────────────────────────────────────────────────────────────────────────┐
│ Instrument Layer (Field Devices) │
│ │
│ ┌────────────┐ ┌────────────┐ ┌────────────┐ ┌────────────┐ ┌──────────┐ │
│ │ Temperature│ │ Pressure │ │ Level gauge│ │ Outdoor │ │ Water │ │
│ │ transmitter│ │ transmitter│ │ Makeup │ │ temperature│ │ quality │ │
│ │ Primary │ │ Primary │ │ water tank │ │ sensor │ │ pH meter │ │
│ │ supply/ret │ │ supply/ret │ │ │ │ │ │(optional)│ │
│ │ Secondary │ │ Secondary │ │ │ │ │ │ │ │
│ │ supply/ret │ │ supply/ret │ │ │ │ │ │ │ │
│ └────────────┘ └────────────┘ └────────────┘ └────────────┘ └──────────┘ │
│ │
│ ┌────────────┐ ┌────────────┐ ┌────────────┐ ┌────────────┐ │
│ │ Circulating│ │ Makeup │ │ Makeup │ │ Selector │ │
│ │ pump │ │ water pump │ │ water valve│ │ switch │ │
│ │ Running / │ │ Running / │ │ On/off │ │ Alarm │ │
│ │ fault │ │ fault │ │ status │ │ signal │ │
│ └────────────┘ └────────────┘ └────────────┘ └────────────┘ │
└─────────────────────────────────────────────────────────────────────────────┘
II. Layered Description of the Block Diagram
| Layer | Components | Functions |
|---|---|---|
| Dispatch Platform Layer | Heating dispatch center SCADA (IFIX, INTOUCH, KingView, ForceControl, etc.) | Receives data uploaded from each heat exchange station, enabling whole-network monitoring, alarm management, historical curves, energy consumption analysis, and remote dispatching. |
| XT-912 Control Layer | XT-912 PLC, local HMI, heat meter/flow meter, VFD, electric control valve | Executes local control logic (quality regulation, quantity regulation, constant-pressure control, safety protection), collects serial instrument data, and uploads data via Ethernet. |
| Instrument Layer | Temperature transmitter, pressure transmitter, level gauge, outdoor temperature sensor, water quality pH meter, pump status, selector switch, alarm signal | Provides field analog, digital, and communication data sources. |
IV. Signal Flow Description
Uplink Acquisition (Instrument → XT-912):
-
Temperature, pressure, level, outdoor temperature → 4-20mA / 0-10V → AI channels
-
Pump running/fault, selector switch, alarm → dry contact → DI channels
-
Heat meter, flow meter → RS485 Modbus RTU → serial port
-
Water quality pH meter → RS485 → serial port
Downlink Control (XT-912 → Actuators):
-
Control valve opening → 4-20mA / 0-10V → AO channels
-
Circulating pump / makeup water pump frequency → 4-20mA → AO channels
-
Pump start/stop, makeup water valve on/off → transistor output → DO channels
Uplink Communication (XT-912 → Dispatch Center):
-
Ethernet port → 3G/4G router / ADSL / community broadband / fiber → Modbus TCP / MQTT / Tengcon IoT protocol → dispatch center SCADA
Local Display:
-
RS232/RS485 serial port → local HMI, displaying process flow diagrams and real-time curves.
Copyright(C)2011 Beijing Tengcon Technology Co.,Ltd. TEL:010-59790086