Input Delay, Pulse Stretching and Oversampling SIMATIC S7-1200, S7-1500, ET 200 https://support.industry.siemens.com/cs/ww/en/view/109736504 Siemens Industry Online Support

This entry originates from Siemens Industry Online Support. The conditions of use specified there apply (www.siemens.com/nutzungsbedingungen). Security Informati on Siemens provides products and solutions with industrial security functions that support the secure operation of plants, systems, machines and networks. In order to protect plants, systems, machines and networks against cyber threats, it is necessary to implement and continuously maintain a holistic, state-of-the-art industrial security concept. Siemens products and solutions only form one element of such a concept. Customers are responsible to prevent unauthorized access to their plants, systems, machines and networks. Systems, machines and components should only be connected to the enterprise network or the internet if and to the extent necessary and with appropriate security measures (e.g. use of firewalls and network segmentation) in place. Additionally, Siemens guidance on appropriate security measures should be taken into account. For more information about industrial security, please visit http://www.siemens.com/industrialsecurity. Siemens products and solutions undergo continuous development to make them more secure. Siemens strongly recommends to apply product updates as soon as available and to always use the latest product versions. Use of product versions that are no longer supported, and failure to apply latest updates may increase the customer s exposure to cyber threats. To stay informed about product updates, subscribe to the Siemens Industrial Security RSS Feed under http://www.siemens.com/industrialsecurity. Contents 1 Introduction... 3... 4 2.1 Input Delay... 4 2.2 Pulse Stretching... 5 2.3 Oversampling... 8 3 Functions Supported by the Different Modules... 10 Entry ID: 109736504, V1.0, 06/2017 2

1 Introduction 1 Introduction Input delay, pulse stretching and oversampling are digital input module functions. These functions pre-process input signals before they are transferred to the CPU. You parameterize these functions in the Hardware Configuration of the corresponding module. The functions are explained in detail in the manual of each module or system. This FAQ shows the relationships and differences between these functions. Chapter 3 also includes a detailed overview of which modules support which functions. Entry ID: 109736504, V1.0, 06/2017 3

2.1 Input Delay General You can use this parameter to suppress signal faults. Signal changes are acquired if they are stable longer than the set input delay time. This is necessary to suppress toggling of the input in the case of switch bouncing. The shorter the set input delay time, the better signal lines have to be shielded against external interference. Figure 2-1: Principle of input delay Signal at terminal Signal in process image of CPU Pulse is shorter than t id and is ignored Pulse is longer than t id and is detected as signal after t id t id : Input delay Note Even if you disable the time delay, there still exists a hardware-specific input delay. Isochronous mode In isochronous mode, the terminal signal is read in at time T i (time for reading in the input data). The read-in time T i refers here to the channel for which no input delay time has been parameterized. In the case of input channels with long input delays, the read-in time is shifted correspondingly. In this way, you can set input delays on individual channels without negatively influencing the possible cycle time. NOTE An isochronous configuration is only possible if at least one channel has no input delay parameterized. Entry ID: 109736504, V1.0, 06/2017 4

2.2 Pulse Stretching General Pulse stretching is a function for stretching a short, digital input signal to the parameterized length. If the input pulse is already longer than the parameterized length, the pulse is not stretched. This is useful if signals with a short length should be recognized, but no bus and/or program cycle time short enough is possible. The figure below shows the principle of pulse stretching with disabled input delay. Figure 2-2: Principle of pulse stretching Pulse stretching time t ps for 1-signal Pulse stretching time t ps for 0-signal Signal at terminal Signal in process image of CPU Pulse is shorter than t ps and is stretched to t ps Pulse is longer than t ps and is not changed t ps : Pulse stretching time NOTE Pulse stretching stretches both the 1-signal and the 0-signal. The actual input signal at the terminal within the pulse stretching time therefore does not lead to a change of the input signal in the process image. Entry ID: 109736504, V1.0, 06/2017 5

During stretching of the 0-signal no new signals are recognized by the module. The edge of a new signal is moved until the ongoing pulse stretching is completed. Short pulses that occur during on ongoing pulse stretching are ignored. The figure below shows the effect of pulse stretching in the case of signals occurring in rapid succession and disabled input delay. Figure 2-3: Effect of pulse stretching with signals occurring in rapid succession Signal terminal Signal in process image of CPU The edge of the second pulse is postponed until the ongoing pulse stretching is completed Short pulses that occur during on ongoing pulse stretching are ignored Recommendation for setting the pulse stretching In order for short pulses to be recognized we recommend the following setting for the pulse stretching time t ps : t ps = 2 (t Buszyklus + t Programmyklus ) Isochronous mode Since in isochronous mode the read-in time for the input data (T i ) is set precisely, you can set a shorter pulse stretching time than in non-isochronous mode. In order to ensure that short pulses are recognized we recommend the following setting for the pulse stretching time t ps in isochronous mode: t ps > Sendetakt T Note During an on-going pulse stretching additional signals are ignored or the edges of additional signals are shifted (see Figure 2-3). Entry ID: 109736504, V1.0, 06/2017 6

Influence of the network environment on the performance Pulse stretching starts after the input delay of a signal. Short pulses are stretched only if they are longer than the parameterized input delay. Figure 2-4: Influence of the input delay on pulse stretching Signal at terminal Signal in process image of CPU Pulse is shorter than t id and is ignored t id : Input delay time t ps : Pulse stretching time Pulse is longer than t id, detected as signal and stretched to t ps Pulse is longer than t id but is missed since pulse stretching of 0-signal of previous pulse is ongoing Entry ID: 109736504, V1.0, 06/2017 7

2.3 Oversampling Function Oversampling is the acquisition of data in equidistant sub-cycles where n subcycles correspond to one send cycle. Oversampling is always useful when you need data acquisition with a high time resolution but no bus and/or program cycle time short enough is possible. With the Oversampling function a send cycle is divided into equidistant sub-cycles: Each sub-cycle acquires 1 bit per channel. Sub-cycles are possible in steps of 2 to 32 (scanning frequency). A sub-cycle is at least 7.8125 μs long. Parameterizing You parameterize oversampling with the "Sampling rate" parameter in the Hardware Configuration of the module. Figure 2-5: Oversampling parameterizing in an ET 200SP digital input module DI 8x24VDC HS Note The interface module or the controller with which the module is being used must support isochronous mode and this must be configured. Sampling interval The duration of a sub-cycle is the sampling interval. In the configuration software you define the send cycle T for the isochronous mode. The send cycle divided by the set sampling rate n Sample provides the sampling interval t Sample of the module. The following formula shows the calculation for the duration of a sub-cycle with 16 sub-cycles and a send cycle of 1 ms: t Sample = T = 1 ms = 62,5 μs n Sample 16 Entry ID: 109736504, V1.0, 06/2017 8

Timing The following figure shows the time sequence of oversampling. The acquired input data of a data cycle (send cycle) is copied to the interface module in the next data cycle and is available in the next data cycle but one of the CPU. Figure 2-6: Principle of the Oversampling function with a sampling rate of 10 sub-cycles per send cycle Table 2-1: Explanation of Figure 2-6 Explanation 1. The send cycle is divided into sub-cycles which each acquire the measured value (here: 10 sub-cycles). 2. The measured values are copied into the IM. 3. The measured values are transferred to the CPU and processed. Further information Detailed information about the Oversampling function is available in the device manual of each module; for example, in the device manual of the ET 200SP Digital Input Module DI 8x24VDC HS: https://support.industry.siemens.com/cs/ww/en/view/109475339/74448593035 Entry ID: 109736504, V1.0, 06/2017 9

3 Functions Supported by the Different Modules 3 Functions Supported by the Different Modules The following table shows which modules available at the publication of this document on July 01, 2017 support the functions concerned. SIMATIC S7-1200 Table 3-1: Supported functions SIMATIC S7-1200 Module Article number Input delay Pulse stretching On-board DIs -- 0.1 µs.. 20 ms No No DI 8x24VDC 6ES7221-1BF32-0XB0 0.2.. 12.8 ms No No DI 16x24VDC 6ES7221-1BH32-0XB0 0.2.. 12.8 ms No No F-DI 8/16x24VDC 6ES7226-6BA32-0XB0 0.8.. 12.8 ms No No DI 8/DQ 8x24VDC 6ES7223-1BH32-0XB0 0.2.. 12.8 ms No No DI 16/DQ 16x24VDC 6ES7223-1BL32-0XB0 0.2.. 12.8 ms No No DI 8x24VDC/ DQ 8xRelay DI 16x24VDC/ DQ 16xRelay DI7DO 8x120VAC/ DQ 8xRelay 6ES7223-1PH32-0XB0 0.2.. 12.8 ms No No 6ES7223-1PL32-0XB0 0.2.. 12.8 ms No No 6ES7223-1QH32-0XB0 0.2.. 12.8 ms No No Oversampling Note With SIMATIC S7-1200, the term "Input filter" is used instead of "Input delay". More information about the modules is available in the system manual "SIMATIC S7-1200 Automation System": https://support.industry.siemens.com/cs/ww/en/view/109478121 Entry ID: 109736504, V1.0, 06/2017 10

3 Functions Supported by the Different Modules SIMATIC S7-1500 Table 3-2: Supported functions SIMATIC S7-1500 Module Article number Input delay Pulse stretching DI 16x24VDC BA 6ES7521-1BH10-0AA0 fixed ~ 3.2 ms No No DI 16x24VDC HF 6ES7521-1BH00-0AB0 0.05.. 20 ms No No DI 16x24VDC SRC BA 6ES7521-1BH50-0AA0 fixed ~ 3.2 ms No No DI 32x24VDC BA 6ES7521-1BL10-0AA0 fixed ~ 3.2 ms No No DI 32x24VDC HF 6ES7521-1BL00-0AB0 0.05.. 20 ms No No DI 16x24..125VUC HF 6ES7521-7EH00-0AB0 0.05.. 20 ms No No DI 16x230VAC BA 6ES7521-1FH00-0AA0 fixed ~ 25 ms No No F-DI 16x24VDC 6ES7526-1BH00-0AB0 0.4.. 3.2 ms No No DI 16/DQ 16x24VDC 6ES7523-1BL00-0AA0 fixed ~ 3.2 ms No No TM Count 2x24V 6ES7550-1AB00-0AB0 0.. 20 ms No No TM PosInput 2 6ES7551-1AB00-0AB0 0.. 20 ms No No TM Timer DIDQ 16x24V 6ES7552-1AA00-0AB0 0.. 0.8 ms No Yes TM PTO 4 6ES7553-1AA00-0AB0 0.. 20 ms No No Oversampling More information about the modules is available in the SIMATIC S7-1500/ET 200MP Manual Collection: https://support.industry.siemens.com/cs/ww/en/view/86140384 Entry ID: 109736504, V1.0, 06/2017 11

3 Functions Supported by the Different Modules SIMATIC ET 200SP Table 3-3: Supported functions SIMATIC ET 200SP Module Article number Input delay Pulse stretching DI 8x24VDC ST 6ES7131-6BF00-0BA0 0.. 20 ms No No DI 8x24VDC BA 6ES7131-6BF00-0AA0 0.. 20 ms No No DI 8x24VDC SRC BA 6ES7131-6BF60-0AA0 0.. 20 ms No No DI 4x120..230VAC ST 6ES7131-6FD00-0BB1 fixed 1.5.. 10 ms DI 16x24VDC ST 6ES7131-6BH00-0BA0 0.. 20 ms No No DI 8x24VDC HF 6ES7131-6BF00-0CA0 0.. 20 ms 0.. 2 s No DI 8x24VDC HS 6ES7131-6BF00-0DA0 0.. 20 ms 0.. 2 s Yes DI 8xNAMUR HF 6ES7131-6TF00-0CA0 fixed 12 ms 0.. 2 s No F-DI 8x24VDC HF 6ES7136-6BA00-0CA0 0.4.. 3.2 ms No No TM Count 2x24V 6ES7138-6AA00-0BA0 0.. 20 ms No No TM PosInput 1 6ES7138-6BA00-0BA0 0.. 20 ms No No TM Timer DIDQ 10x24V 6ES7138-6CG00-0BA0 0.. 0.8 ms No Yes TM Pulse 2x24V 6ES7138-6DB00-0BB1 0.. 20 ms No No No Oversampling No More information about the modules is available in the SIMATIC ET 200SP Manual Collection: https://support.industry.siemens.com/cs/ww/en/view/84133942 SIMATIC ET 200eco PN Table 3-4: Supported functions SIMATIC ET 200eco PN Module Article number Input delay Pulse stretching 8DI x 24VDC 4xM12 6ES7141-6BF00-0AB0 fixed ~ 3 ms No No 8DI x 24VDC 8xM12 6ES7141-6BG00-0AB0 fixed ~ 3 ms No No 16DI x 24VDC 8xM12 6ES7141-6BH00-0AB0 fixed ~ 3 ms No No 8DI/8DO x 24VDC / 1.3A 8xM12 6ES7147-6BG00-0AB0 fixed ~ 3 ms No No Oversampling More information about the modules is available in the manual "SIMATIC Distributed IO System ET 200eco PN": https://support.industry.siemens.com/cs/ww/en/view/29999018 Entry ID: 109736504, V1.0, 06/2017 12

3 Functions Supported by the Different Modules SIMATIC ET 200pro Table 3-5: Supported functions SIMATIC ET 200pro Module Article number Input delay Pulse stretching 8DI x 24VDC 6ES7141-4BF00-0AA0 fixed 1.2.. 4.8 ms No No 8DI x 24VDC HF 6ES7141-4BF00-0AB0 0.5.. 20 ms 0.. 2 s No 16DI x 24VDC 6ES7141-4BH00-0AA0 fixed 0.7.. 4.8 ms No No 8/16 F-DI DC24V 6ES7148-4FA00-0AB0 0.5, 3, 15 ms No No 4DIO/4DO x 24VDC / 0.5A 4DI/4DO x 24VDC / 0.5A 6ES7143-4BF00-0AA0 fixed 1.2.. 4.8 ms No No 6ES7143-4BF50-0AA0 fixed ~ 3 ms No No 4/8 F-DI4 F-DO 6ES7148-4FC00-0AB0 0.5, 3, 15 ms No No F switch 6ES7148-4FS00-0AB0 fixed ~ 3 ms No No Oversampli ng More information about the modules is available in the manual "SIMATIC Distributed IO System ET 200pro": https://support.industry.siemens.com/cs/ww/en/view/21210852 SIMATIC ET 200AL Table 3-6: Supported functions SIMATIC ET 200AL Module Article number Input delay Pulse stretching DI 8x24VDC 4xM12 6ES7141-5AF00-0BA0 fixed ~ 3 ms No No DI 8x24VDC 8xM8 6ES7141-5BF00-0BA0 fixed ~ 3 ms No No DI 16x24VDC 8xM12 6ES7141-5AH00-0BA0 fixed ~ 3 ms No No DIQ 4+DQ 4x24VDC/0.5A 4xM12 DIQ 4+DQ 4x24VDC/0.5A 8xM8 DIQ 16x24VDC/0.5A 8xM12 6ES7143-5AF00-0BA0 fixed ~ 3 ms No No 6ES7143-5BF00-0BA0 fixed ~ 3 ms No No 6ES7143-5AH00-0BA0 fixed ~ 3 ms No No Oversampling More information about the modules is available in the SIMATIC ET 200AL Manual Collection: https://support.industry.siemens.com/cs/ww/en/view/95242965 Further information Further differences between the BA, ST, HF and HS modules of the ET 200SP and ET 200MP are given in the following entry: https://support.industry.siemens.com/cs/ww/en/view/109476914 Entry ID: 109736504, V1.0, 06/2017 13