15. Handy Instruction Design Examples temperature, it still needs to take more than 1 hour and 15 minutes to reach the target temperature with ± 1 ℃ accuracy. It seems that we have chosen the right environment, but the sampling time is too long, resulting in the extension of heating time. Therefore, we modify the sampling time to 2 seconds, i.e. D12 = K20 (2s) and D30 = K2000 (= D12*100). The results are shown in the diagram below. From the diagram above, we see that the control system becomes too sensitive and leads to up and down fluctuations. Therefore, we modify the sampling time to 4s, i.e. D12 = K40 (4s) and D30 = K4000 (= D12*100). The results are shown in the diagram below.
From the diagram above, we see that the overall control time has been shorten as 37 minutes and no exceeding or fluctuations occur. The basic requirements of the control system are satisfied. DVP-PLC Application Examples 15-21