From an email earlier this month, Dick Caro writes:
I have written several articles on FDT/DTM. Originally, I was quite negative about this technology, but after being "educated" by several field instrument suppliers I have finally resolved the important differences between FDT/DTM and EDDL. I thought that this information would be good to share with my fellow SP104 committee members.The most basic difference between them is that -- * FDT/DTM allows the instrument supplier to format the HMI screen display for that instrument
* EDDL allows the HMI supplier (typically the DCS vendor) to format the screen display for all field instrumentsI have polled several end users with this generality, and they mostly agree that it is more important that they not train their process operators for each type of field instrument. They want the DCS supplier to control the look-and-feel of the HMI.However, in my conversations with some instrument suppliers, I find that there are some diagnostic and calibration displays that cannot be made available via EDDs (they tell me). They find that they can COMPLEMENT the EDD with their own tools by using FDT/DTM. I have no reason to doubt their conclusion. While DCS and independent HMI suppliers can offer a wide variety of graphic tools, I am sure that creative instrument suppliers knowing the deep technology of their sensing and actuation methods can create high added value displays that only they know about, particularly for diagnostics.There are many other technical and procedural differences that may be important in competitive situations, but my overall conclusion is that these are COMPLEMENTARY technologies.
