GE RX3i PROFINET User Manual

Also see for RX3i PROFINET: User manual Quick start guide

Contents

GE RX3i PROFINET User Manual Manual pdf 61 page image

Chapter 5. Operations54 PACSystems* RX3i PROFINET IO-Scanner User Manual GFK-2737F5.2.2 Data CoherencyThe RX3i PNS provides coherency at a submodule basis only. This means that output data from a singleI/O Controller for multiple modules in the PNS rack might not be applied by the PNS during the sameoutput scan. Likewise, input data from all modules read in a single PNS input scan may not be producedby the PNS during the same PROFINET I/O cycle.5.2.3 Sampling RateThe PROFINET Device Update Rate should be taken into consideration with regard to I/O devices in aScanner rack. I/O data that changes quickly, such as status bits that represent an event in a module andare only set for one scan of the module, may be missed if the update period spans multiple scans of themodule. In some cases, other functionality may be utilized to capture momentary events. For example,High-Speed Counter Over Range, Under Range, Overflow, and Underflow status conditions can be latchedby configuring an unused counter to mirror the operating counter and assigning the event condition as astrobe source. The corresponding strobe status and acknowledge bits may be used to monitor andacknowledge the condition.5.2.4 Differences from Main (CPU) RackThe following CPU operations are not supported or exhibit different behavior than when used with I/Omodules in a CPU rack.5.2.4.1 InterruptsInterrupts are not supported for I/O modules in a PNS rack. Service Requests that disable, enable,suspend, or resume interrupts have no effect. Interrupt driven Logic blocks cannot be used with I/Omodules in a PNS rack, and interrupt status bits should be ignored.5.2.4.2 Do I/O and Suspend I/ODo I/O and Suspend I/O operations are limited to updating or suspending the data between the CPU andPNC. The PROFINET I/O scan is not altered (that is, DO_IO data is not exchanged with the PNS any fasterthan the PROFINET update rate allows).