WECON LX2N-4PT PLC Extend Module Temperature Test
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The LX2N-4AD-PT analog block amplifies the input from four platinum temperature sensors (PT 100, 3 wire, 100 Q) and converts the data into 12 bit reading's stored in the Main Processing Unit (MPU). Both Centigrade (°C) and Fahrenheit (°F) can be read. Reading resolution is 0.2°C to 0.3°C / 0.36°F to 0.54°F The LX2N-4AD-PT occupies 8 points of I/O on the LX2N expansion bus. The 8 points can be allocated from either in-puts or outputs. The LX2N-4AD-PT draws 30mA from the 5V rail of the MPU or powered extension unit. LX2N-4PT consume 5V voltage from LX2N main unit or active extension unit,90mA...

The cable of the PT 100 sensor or a twisted shielded cable should be used for the analog input cable. This analog input cable should be wired separately from power lines or any other lines which may induce noise The three wire method improves the accuracy of the sensors by compensating voltage drops. If there is electrical noise, connect the frame ground terminal (FG) with the ground terminal. Connect the ground terminal on the LX2N-4AD-PT unit with the grounded terminal on the base unit. Use class 3 grounding on the base unit, if grounding is Either an external or the 24V built-in supply...

NOTE: Preset ranges are selected by an appropriate setting in buffer memory of the analog block.Current/Voltage input selection must match the correct input terminal connections. Miscellaneous Item Isolation Total points Description Photo-coupler isolation between analog and digital circuits. DC/DC converter isolation of power from LX2NMPU. No isolation between analog channels. 8 points taken from the LX2N expansion bus (can be either inputs or outputs) 4.4 Buffer memory assignment BFM Content CH1 to CH4 Averaged temperature reading to be *#1→#4 averaged (1 to 4,096) Default = 8 *#5→#8 CH1...

b7 b6 b5 b4 b3 b2 b1 b0 High Low High Low High Low High Low Not used CH4 CH3 CH2 CH1 Low: Latches ON when temperature measurement data goes below the lowest temperature measurement limit. High:Turns ON when temperature measurement data goes above the highest temperature measurement limit, or when a thermocouple is disconnected. When an error occurs the temperature data before the error is latched. If the measured value returns to within valid limits the temperature data returns to normal operation. (Note: The error remains latched in (BFM #28)) An error can be cleared by writing K0 to BFM...

5. System block diagram data status offset values Analog Input Cyclic switching' In the program shown below, the LX2N-4AD-PT block occupies the position of special block number 2 (that is the third closest block to the programmable controller). The averaging amount is four. The averaged values in degrees C of input channels CH1 to CH4 are stored respectively in data registers DO to D3. Identification code When identification code is K2040, M1 = ON This initial step checks that the special function block placed at position 2 is actually an LX2N-4AD-PT, i.e. its unit identification number is...

Number of samples is changed four on CH1 to CH4. Transfer the averaged temperature value in °C to the data This step is the actual reading of the LX2N-4AD-PT input channels. It is essentially the only program step which is needed. The "TO" instruction in this example, sets the input channels, CH1 to CH4, to take the average reading of four samples. The "FROM" instruction reads the average temperatures (BFM #5 to #8) for input channels CH1 to CH4 of the LX2N-4AD-PT. If direct temperature readings are required BFM #9 to #12 should be read instead, ex. block No.2 BFM number destination words...

Electromagnetic compatibility or EMC must be considered before using the L X2N-4AD-PT. Mitsubishi recommend that the PT 100 sensors used, should be fitted with a form of seild or screening as protection If some form of cable protection is used, the "Shield" must be terminated at the I ^ 11 ~± I terminals as shown in Because of the delicate nature of all analog signals, failure to take good EMC precautions could lead to EMC noise induced errors ; up to ±10% of actual values. This is an absolute worst case figure, users who do take good precautions can expect operation within normal...