QQD multi-channel digital display universal input can be used in conjunction with sensors and transmitters, greatly reducing the number of backup meters. The QQD multi-channel digital display meter realizes the measurement, display, alarm control, and transmission output of physical quantities such as temperature, pressure, flow rate, and liquid level. Complete network communication function, enabling high-speed and efficient bidirectional data exchange with computers. The time to read measurement data is less than 10mS. Provide technical support for testing software, configuration software, and application software. Capable of remote debugging, diagnosis, and data collection. Multiple protection and isolation design, strong anti-interference ability, and high reliability. It has error correction and fault detection functions for input signals from sensors and transmitters, effectively improving the measurement and control performance of the system.

• Calculation between channels
The application where channels are interrelated and require operations such as addition, subtraction, and comparison.
• Input signal
The dual channel universal input can freely change the input signal type of the instrument. By adopting the new jumper free technology, the instrument can be changed from one input signal to another by simply setting the internal parameters of the instrument.
• Correction
The correction function of sensors effectively reduces errors caused by various reasons of sensors, transmitters, or instruments. Improve the measurement and control accuracy of the system.
Thermocouple cold junction compensation
When the input signal is a thermocouple, automatic cold junction compensation is performed. Compensate temperature between 0-50 ℃.
• Sensor fault handling
When the instrument determines that the signals from the sensors and transmitters are in a fault state, the instrument will use preset values as input values for alarm output and transmission output to prevent abnormal equipment operation such as misoperation interlocking and shutdown.
• Alarm output
4-point alarm, with independent setting of alarm sensitivity. Each alarm point can be assigned to a designated channel through setting. The 2-channel instrument has differential and sum value alarm functions.
• Transmission output
Two way transmission output, the instrument converts the measured values after measurement calculation and correction into various types of isolated standard current or voltage signal outputs, which are provided to other instruments or computers for use. The transmission output can independently set the upper and lower limits of the range. The 2-channel instrument has differential and sum value transmission output functions.
• Digital filtering
Prevent unstable instrument display values due to the influence of the sensor's natural frequency, external vibration conduction, and unpredictable interference.
• Communication interface
A fully transparent, high-speed, and efficient networked communication interface enables data transmission and control between computers and instruments.

• Input signal: (compatible with one instrument)
Thermocouples: K, S, R, E, J, T, B, N, etc
Thermistors: Cu50, Pt100, Cu100, BA1, BA2, G53.
Linear voltage: 0-5V, 1-5V, 0-1V, 0.2-1V, 0-100mV, 0-60nV
0-20mV, etc
Linear current (requires external shunt resistor): 0-10mA, 0-20mA, 4-20mA, etc
Linear resistance: 0-80 Ω, 0-400 Ω
Expansion specification: Allow users to specify an additional input specification while retaining the above input specifications
Grid (division table may need to be provided)
• Measurement accuracy
0.2 level (thermal resistance, linear voltage, linear current, and thermocouple input with copper resistance compensation)
Or when compensating for the cold end at freezing point)
0.2% grade F.S ± 2 ℃ (when thermocouple input is used and internal components of the instrument are used for temperature compensation at the cold end)
Response time ≤ 0.5 seconds (when setting the digital filtering parameter dL=0)
• Transmission output linear current output: 0-10mA, 0-20mA, 4-20mA can be defined
• Alarm function
Relay contact switch output (normally open+normally closed): 250VAC/2A, 30DC/1A;
SSR voltage output: 12VDC/30mA (used to drive SSR solid-state relays).
Communication interface (optoelectronic isolation)
RS-232 and RS-485 standards, please specify when ordering
Instrument address 0-99 can be set
Communication speeds of 2400, 4800, 9600, 19200 can be selected through settings
Supporting testing software, providing technical support for configuration software and application software
• Electromagnetic compatibility
IEC61000-4-4 (Electrical Fast Transient Pulse Group), ± 2KV/5KHz;
IEC61000-4-5 (Surge), 4KV
• Isolation and voltage resistance
The voltage between the power supply terminal, relay contact, and signal terminal is ≥ 2300V;
Isolated weak current signal terminals with a voltage of ≥ 600V between them
• Power supply voltage:
Switching power supply 100-240VAC, -15%,+10%/50-60Hz or switching power supply
24VDC,-15%,+10%
• Power consumption: ≤ 5W
• Environmental temperature: 0-50 ℃
• Environmental humidity: 10% -90% RH, avoid strong corrosive gases