1/12/2024 6:43 AM | |
Joined: 9/11/2014 Last visit: 8/7/2024 Posts: 742 Rating: (29) |
Hi, OUTPUT frequency: Here examples from SIemens how to get the scantime of a program: https://support.industry.siemens.com/cs/de/de/view/109783502 (Goto scantime in this collection then you find how to get it) Basically LOGO! is not the best controller for fast or real time application. The typical scantime of a LOGO! is <0.1 ms per functionblock. If you have used all 400 function blocks in a LOGO! Program, then the theoretical scantime is 40ms. If you need output signals, then with relay outputs this frequency is much to fast for a relay. According to the LOGO! Manual the max output frequency is: for relay outputs: 2Hz at ohmic load Input frequency: If there is a additional functionblock between the fast input and the up/down counter, then the it also depends on the LOGO! scan time. For fast and/or real time application better to use S7-1200/1500. This controller can create a much faster output signal and can read much faster input signals. Hope this helps. |
1/13/2024 7:38 AM | |
Joined: 10/15/2022 Last visit: 8/1/2024 Posts: 66 Rating: (2) |
Hello I have made one sample program to test pulse rates. There are three frequency and pulse counters. The first one (A) is cycle time dependent, the second one (B) uses an asynchronous pulse generator whose times can be changed and the third one (C) counting pulses from input I3. By default the operation lasts 10 seconds. This time can also be changed. ESC+Arrow_Up key triggers the timer, ESC+Arrow_Down key resets it and the all counters. The operation of output Q3 can be enabled/disabled with ESC+Arrow_Left key. The output (relay) blinked pretty crazy (10 ms on, 10 ms off in case). This is controlled by an asynchronous pulse generator (B). Counter C taking readings from input I3, where Q3 is connected with external wire. The frequency of pulse counter A even depends on whether or not you are also online at the same time. I managed to get a pulse rate of about 1535Hz (without being online). For pulse counter B, it was 50 Hz (can generate up to 100 Hz). The program has been tested on a 12/24V controller 6ED1052-1MD08-0BA1 with relay outputs. In simulation I had much lower numbers (maybe it depends on the speed of the computer itself). Even though the relay may operate faster than stated on the data sheet, it should still be within the permissible limits. Andrus P.S. I've been playing with an "Eaton easy4" controller with transistor outputs (E4-DC-12TC1). Its two outputs do support PWM (up to 200 Hz) and are able to output pulses (1:1 ratio , up to 5 kHz). The latter can be used to control a stepper motor (via the motor driver). * Translated with DeepL.com (free version)
AttachmentPulse_test_demo_V8.zip (225 Downloads) |
Last edited by: Andrus_Saar at: 01/13/2024 07:43:05Last edited by: Andrus_Saar at: 01/13/2024 07:51:27Last edited by: Andrus_Saar at: 01/13/2024 08:07:44 |
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