Application: Sub-Station Automation
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sibym2000
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Sunday 24 December 2006 5:36:33 am |
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Application: Sub-Station Automation
Requirement from the system: Monitoring & control, time stamped data from Intelligent Electronic devices viz., protection relays, motor managers, power monitors.
PLC under consideration: Allen Bradley Controllogix
Protocol between PLC & IED's: DNP 3.0 Level 2 (time stamped data from the IED's need to be transferred into CPU and further to RSView SE SCADA)
Protocol between PLC & SCADA: DNP 3.0 over Ethernet Communication.
Problem being faced: PSFT 1756-DNP master protocol specifies that "Event data rec'd from the slave devices updates the module database (Date & Time stamping is not stored or used by module"
Query:
1. does it mean, 1756-DNP doesnot supports time stamp events when confiured as Master to the slave IED's. How can one utilize the event time stamping feature of DNP protocol from this module. If the module supports event time stamping, how many data points can it store.
2. same query applies for 1756-DNPSNET Module.
3. any limitation w.r.t module placement in the controllogix rack system
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esyme
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Wednesday 03 January 2007 4:02:18 pm |
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RE:Application: Sub-Station Automation
Problem being faced: PSFT 1756-DNP master protocol specifies that "Event data rec'd from the slave devices updates the module database (Date & Time stamping is not stored or used by module"
Query:
Q1. does it mean, 1756-DNP does not supports time stamp events when confiured as Master to the slave IED's. How can one utilize the event time stamping feature of DNP protocol from this module. If the module supports event time stamping, how many data points can it store.
A: The module by default will discard the time stamp received from the DNP message and just update the associated point with the latest value. You can configure and option called "Pass Event Messages to PLC" within the configuration file for the module. This will cause the latest value to update the associated point in the module database, but also the event will be passed to the CLX processor using a 9903 block. This 9903 block will contain the information from the event, and the 48 bit DNP time stamp. This time stamp can then be used for logging at the SCADA end. Up to 100 of these events can be stored by the module.
Q2. same query applies for 1756-DNPSNET Module.
A: The MVI56-DNPSNET module is a DNP Ethernet Server only (slave). This module does not have any Client (master) capability and cannot poll data from IED units.
Q3. any limitation w.r.t module placement in the controllogix rack system
A: The module can be placed in any location within a CLX system, however if the module is placed in a remote rack over ControlNet special consideration must be given to the design of your CNET network. This module has a large (500bytes input/ 496 bytes output) data image. On some CNET networks, this may make configuration of the Control Net network difficult. If placing the module in a remote rack, you may need to increase RPI times, NUT times, or in some cases even have a dedicated CNB(R) module to not disturb other I/O in the system.
Remote racks over EtherNet I/P do not have these same issues, but cannot be used with Hot Standby systems since the module is an I/O module.
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