7/8/2013 6:02 PM | |
Posts: 6 Rating: (0) |
Dear all, I have a pressure sensor Siemens 7MF1565-... connect to PLC 1214C to measure the level of fresh water in a box which heigh is 300mm. My sensor has range 0 - 0,6bar (I think its range too high) and send current 4-20mA to PLC. I used a shunt registor 500ohm to connect to 0-10V analog input of PLC. In TIA Portal V11, I use 2 instruction NORM and SCALE to read the level. At first I set the NORM and Scale values like that: Norm : Min = 6279 Max = 7099 Scale: Min = 19 (mm) Max = 250 (mm) After read and set the limits, I checked the linearity of sensor with several point between limits and they are all good. But after 1h, I checked again and saw that the value read from PLC had changed difference with limits I set. In detail: Min : 6211 Max: 7030 So at the min value of PLC read, the scale value is -0.156 instead of 19, and max value display 230,56 instead of 250. Although it all still linear but the value be read has changed. I try with analog module Sm1231 4HF30 and got the same behavior. I dont understand why. I have attach the excel file for you understand. Please help me what's wrong? PLC or Sensor or Wiring? Thank you very much
AttachmentSensor_Trend.zip (210 Downloads) |
7/9/2013 7:20 AM | |
Joined: 4/17/2012 Last visit: 8/30/2024 Posts: 474 Rating: (10) |
Hi, i also faced same problem by using this NORM and SCALE block . instead of that i created my own scalling block. Y=Mx+C Attachmentfor_ref.zip (224 Downloads) |