NI PXI-6551數字I/O
品牌：NI
型號：NI PXI-6551
產(chǎn)品說(shuō)明：數字I/O
NI PXI-6551數字I/O中文資料：
NI PXI-2501多路復用器開(kāi)關(guān)模塊在任何固定溫度下，精度都相對穩定。對于需要更高精度的應用，提供以下建議：?對于CPU溫度穩定的安裝，測量24小時(shí)內的時(shí)間漂移量，然后在梯形圖程序中編程“校正”因子，定期增加或減少秒數，以保持CPU時(shí)間準確。在這種情況下使用的指令是服務(wù)請求#7，“更改/讀取日時(shí)鐘時(shí)間”。NI PXI-2501在適當的時(shí)間，服務(wù)請求將讀取TOD時(shí)鐘，ADD指令將向其添加校正值，另一個(gè)服務(wù)請求將向TOD時(shí)鐘寫(xiě)入新值。這種方法的一個(gè)可能缺點(diǎn)是，如果更換CPU，則必須確定新的校正系數。此外，這種方法受到溫度變化的影響，因此它的成功取決于保持CPU的環(huán)境溫度穩定。如果需要更高的精度，PLC可以連接到第三方解決方案，如無(wú)線(xiàn)電鏈路或全球定位系統（GPS）衛星系統。NI PXI-2501
英文資料
The accuracy is relatively stable at any fixed temperature. For applications that require greater accuracy, the following suggestions are furnished: ? For an installation where the temperature of the CPU is stable, measure the amount of time drift for a 24 hour period, then program a “correction” factor into the ladder program to add or subtract seconds periodically to keep the CPU time accurate. The instruction to use in this case is Service Request #7, “Change/Read Time-of-Day Clock.” At the appropriate time, a Service Request would read the TOD clock, an ADD instruction would add the correction value to it, and another Service Request would write the new value to the TOD clock. A possible drawback to this method is that if you replace your CPU you will have to determine a new correction factor. Also, this method is affected by temperature changes, so its success is based on holding the CPU’s ambient temperature stable.If more accuracy is needed, the PLC could be interfaced to a third party solution such as a radio link or Global Positioning System (GPS) satellite system.NI PXI-2501
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