SPC3

PROFIBUS Interface Center

 

 

 

 

 

 

5.4 Watchdog Timer

5.4.1 Automatic Baud Rate Identification

The SPC3 is able to identify the baud rate automatically. The „baud search“ state is located after each RESET and also after the watchdog (WD) timer has run out in the ‘Baud_Control_state.’

As a rule, SPC3 begins the search for the set rate with the highest baud rate. If no SD1 telegram, SD2 telegram, or SD3 telegram was received completely and without errors during the monitoring time, the search continues with the next lowest baud rate.

After identifying the correct baud rate, SPC3 switches to the “Baud_Control” state and monitors the baud rate. The monitoring time can be parameterized (WD_Baud_Control_Val). The watchdog works with a clock of 100 Hz (10 msec). The watchdog resets each telegram received with no errors to its own station address. If the timer runs out, SPC3 again switches to the baud search state.

5.4.2 Baud Rate Monitoring

The located baud rate is constantly monitored in ‘Baud_Control.’ The watchdog is reset for each error-free

telegram to its own station address. The monitoring time results from multiplying both ‘WD_Baud_Control_Val’ (user sets the parameters) bythe time base (10 ms). If the monitoring time runs out, WD_SM again goes to ‘Baud_Search’. If the user carries out the DP protocol (DP_Mode = 1, see Mode register 0) with SPC3, the watchdog is used for the “DP_Control’ state, after a ‘Set_Param telegram’ was received with an enabled response time monitoring ‘WD_On = 1.’ The watchdog timer remains in the baud rate monitoring state when there is a switched off ‘WD_On = 0’ master monitoring. The PROFIBUS DP state machine is also not reset when the timer runs out. That is, the slave remains in the DATA_EXchange state, for example.

5.4.3 Response Time Monitoring

The ‘DP_Control’ state serves response time monitoring of the DP master (Master_Add). The set monitoring times results from multiplying both watchdog factors and multiplying the result with the momentarily valid time base (1 ms or 10 ms):

TWD = (1 ms or 10 ms) * WD_Fact_1 * WD_Fact_2 (See byte 7 of the parameter setting telegram.)

The user can load the two watchdog factors (WD_Fact_1, and WD_Fact_2) and the time base that represents a measurement for the monitoring time via the ‘Set_Param telegram’ with any value between 1 and 255.

EXCEPTION: The WD_Fact_1=WD_Fact_2=1 setting is not permissible. The circuit does not check this setting.

Monitoring times between 2 ms and 650 s - independent of the baud rate - can be implemented with the permisible watchdog factors.

If the monitoring time runs out, the SPC3 goes again to ‘Baud_Control,’ and the SPC3 generates the ‘WD_DP_Control_Timeout-Interrupt’. In addition, the DP_State machine is reset, that is, generates the reset states of the buffer management.

If another master accepts SPC3, then there is either a switch to ‘Baud_Control” (WD_On = 0), or thereis a delay in ‘DP_Control’ (WD_On = 1), depending on theenabled response time monitoring (WD_On = 0).

SPC3 Hardware Description

V1.3

Page 25

Copyright (C) Siemens AG 2003 All rights reserved.

 

2003/04

Page 26 Page 28
Page 27
Image 27
Siemens SPC3 manual Watchdog Timer, Automatic Baud Rate Identification, Baud Rate Monitoring, Response Time Monitoring
Page 26 Page 28

SPC3 specifications

Siemens SPC3 is a state-of-the-art solution designed to enhance industrial automation, providing businesses with a robust platform for managing complex processes efficiently. This device epitomizes Siemens' commitment to innovation, blending cutting-edge technology with user-friendly features to deliver optimized performance across various applications.

One of the standout features of the Siemens SPC3 is its advanced processing capabilities. Equipped with high-performance processors, it can handle various tasks simultaneously, ensuring seamless operation even in demanding environments. This performance is complemented by enhanced memory capacity, which allows for increased data handling and improved execution speed, crucial for real-time monitoring and control applications.

The Siemens SPC3 also integrates a modular design, enabling flexibility and scalability. This characteristic allows users to customize their systems according to specific operational needs, adding or removing components as required. This adaptability is particularly beneficial for businesses that aim to scale their operations without incurring the substantial costs associated with overhauling existing systems.

Furthermore, the SPC3 employs the latest communication technologies, ensuring interoperability with various devices and systems. It supports industry-standard protocols, facilitating efficient data exchange between components. This connectivity is vital for establishing smart factories and enhancing overall productivity by creating a unified ecosystem.

Another significant aspect of the Siemens SPC3 is its focus on security. As cyber threats in industrial settings become increasingly sophisticated, Siemens prioritizes safeguarding user data and system integrity. The SPC3 incorporates advanced security features, including encryption and access control measures, to protect against unauthorized access and ensure data confidentiality.

Siemens has also emphasized ease of use in the SPC3. The interface is designed to be intuitive, allowing operators to navigate and configure the system effortlessly. Coupled with comprehensive software tools, users are empowered to implement changes swiftly while minimizing downtime.

In terms of energy efficiency, the SPC3 incorporates technologies that allow for optimized energy consumption, aligning with sustainability goals prevalent in today’s industries. By reducing energy waste, businesses not only lower operational costs but also contribute to environmental conservation.

In summary, Siemens SPC3 represents a significant advancement in industrial automation technology. Its high-performance processing, modular adaptability, advanced communication capabilities, robust security measures, and user-friendly design make it an ideal choice for businesses striving for efficiency and innovation in their operations. The SPC3 is more than just a control device; it is a comprehensive solution that meets the evolving demands of modern industries.
Top Page Image Contents