MIME 4450 Lec 15 10 22 26
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Overview
Evans outlines upcoming assignments and a hands-on project combining a vision-enabled robot, a Siemens PLC, and an HMI, with students choosing between existing lab robots and roughly $1,500 Jetson NX-based units. He also explains safety PLC redundancy and implementation, then walks through Siemens TIA Portal version 19/20 HMI setup pitfalls, including password precautions, panel compatibility, certificates, and rebuild procedures.
Key takeaways
- A complete student automation project can combine a vision-enabled Jetson NX robot, a Siemens PLC, and an HMI; the roughly $1,500 robot offers a lower-cost alternative to a $40,000 industrial robot.
- Dual-channel safety inputs must agree, and a mismatch should stop the process; triple modular redundancy instead uses three-channel voting to tolerate one fault while two channels still agree.
- Safety PLCs became permissible under NFPA 79 in the United States in 2003, and integrating safety logic can avoid expensive retrofits when safety requirements emerge later.
- In Siemens TIA Portal version 20, upgrading an existing safety project can preserve required modules that may not be included when building a new project from scratch.
- For a first Siemens HMI download, rebuilding all hardware and software from the device context menu is more reliable than relying only on the toolbar compile buttons.
- Practical HMI designs can layer a button and indicator light in the same screen location, while response times may need configuration because default behavior can take one or two seconds.
Chapters
- Week 4 through week 7 materials include a 10-question, 50-point assignment based on chapters 3 and 4 of the spreadsheet manual.
- The manual's answers are at the back, and Evans encourages students to match questions with answers while still learning the material.
- A separate week 7 and week 8 robot problem was generated with ChatGPT; most questions allow multiple valid solutions.
- Eight of 12 robots had arrived, with 11 intended for student use across North Engineering rooms 1100 and 2350 and one reserved for Evans.
- The robot costs about $1,500, compared with approximately $40,000 for an industrial robot; Evans says the software is more valuable than the physical unit.
- The platform combines a 3D camera and robot, and can be connected to a Siemens PLC and HMI; the software primarily uses Python, with some C++.
- Students can combine an existing lab robot, camera, and PLC, or connect a Jetson NX robot and camera to a PLC.
- Evans also encourages safety PLC projects, noting that safety PLC programming is a useful resume skill despite setup complications.
- Students can reserve one of the boxed robots by labeling it, with equipment expected to be ready in room 1100 after the break.
- The lab has eight safety PLC units upstairs and another unit downstairs, with related examples in chapter 26 of the lab book.
- The larger relays shown with the equipment are not safety relays and do not hold the supplied 22-gauge solid wire securely.
- Evans describes a vendor-derived safety PLC project that a student first wired successfully in April 2021; students may reproduce only part of it or build a different circuit.
- A typical safety input uses two channels that must change state together; a mismatch, such as one input activating without the other, triggers rejection or shutdown.
- Triple modular redundancy uses three channels and voting: two agreeing channels can keep a system running while raising an alarm, while only one working channel requires shutdown.
- The lab's safety approach is fail-safe: a detected fault stops the process rather than allowing continued operation.
- Evans cites a $135 million judgment involving Kansas City Power & Light and Allen-Bradley/Rockwell over an explosion and disputed safety equipment.
- He connects serious incidents such as Three Mile Island and Chernobyl with operator errors made worse by inadequate HMI visibility.
- Evans says NFPA 79 allowed safety PLCs in the United States beginning in 2003; before then, safety functions generally relied on external circuits or modules.
- Safety PLC designs double-check inputs, outputs, and program logic, separating safety logic from ordinary PLC logic while allowing selected variables to be shared.
- The safety program must be password protected; when ownership of a machine transfers, Evans says the password and legal responsibility should transfer with documented sign-off.
- Two-hand press controls require both buttons to activate within a set interval, and releasing either button stops the press to keep an operator's hands clear.
- The existing wiring diagram uses matching labels such as A3+ to identify connections between terminals and devices; following the labels and downloading the supplied program should make the example work.
- Most inputs are category 3, while a category 4 input expects a manufacturer-supplied 24-volt signal with a diagnostic notch.
- For Siemens TIA Portal version 20, Evans recommends upgrading an older project first so its safety modules come along, then deleting unneeded program content instead of starting from scratch.
- Evans says safety PLC experience can distinguish a candidate from someone whose resume only lists general PLC programming.
- Safety features can extend beyond PLC I/O to redundant safety networks and robot teach pendants that limit motion to a safe mode.
- For new system design, he recommends considering a safety PLC early when requirements are uncertain, since adding safety capability later can require costly hardware and programming changes.
- Evans points students to the Rubik's Cube project documentation for HMI examples and notes that Siemens version 20 makes simulated HMI setup more difficult.
- The student software license works indefinitely, while the annual version expires after one year; he advises avoiding passwords during project initialization.
- A blank Siemens memory card can overwrite a password-protected PLC program, but the PLC should remain powered for about five minutes during the reset process.
- Evans advises against using a 10-inch Siemens panel because its drivers may not work correctly with version 20; he names 9-, 12-, and 15-inch alternatives.
- A blank project 3 template from the MIME 4450 site can simplify setup for a new 1215 processor with firmware 4.7.
- HMI setup may require certificate and PG/PC interface configuration; the instructions differ between versions 19 and 20.
- For the first download, Evans recommends right-clicking the project device and selecting rebuild or compile for all hardware and all software, then downloading.
- He warns that the toolbar compile buttons may not perform the same full cleanup as rebuilding all hardware and software.
- The Rubik's Cube project materials include step-by-step HMI screen setup, button properties, and examples such as setting a bit when a button is pressed.
- The Simon Says example stores button locations in an array and overlays a light and a button at the same screen position using separate layers.
- The sample program works but may require pressing reset twice, and HMI timing can create issues if interactions are not configured carefully.
- Evans contrasts modern expectations near a tenth of a second with older Wonderware systems that could take 10 to 15 seconds; Siemens HMI defaults may take one or two seconds.
- Evans says the Rubik's Cube HMI documentation reflects problems encountered after Siemens software changes from version 16 through versions 19 and 20.
- After the break, planned work includes coding the small robots, potentially in Python, and integrating the robot, vision system, and PLC.
- Completed projects should also produce reports and database records; teams will need to decide whether the PLC coordinates the robot and vision system or those components communicate directly.
Transcript excerpt
0:03 So, um on your on your website, I put uh some some uh two more assignments and Um, here they are. This is kind of a a not I hate to use the word gift, but it uh will helped a little bit with these other ones being kind of uh Okay, so projects under projects uh week four, week five, week six, week
0:54 seven. the um 10 questions, 50 points. And the clue here is that if you go under the hybrid PLC 4450 class and then the Cognic School and uh Okay. Uh, so I um I want to look at in in the cognitive
1:44 spreadsheet. Um, so let's just look under content spreadsheet. All right. So let's just look under that uh silver. This is the one that has the um manual, the spreadsheet manual. And if you look here
2:32 um this is separated out into um chapter and then questions at the end of the chapter. Chapter and question in the chapter, chapter and questions in the chapter. And I took questions from three and four here. Okay, the dirty little secret is the answers are at the end. Okay, so all you have to do is find the right question with the right answer, line it up, and you're all set. You can read through this if you want to, but I'm giving you a heads up that the answers are at the back of the book. Okay, that being said, it'd be nice for you to
3:22 you should learn about some of these things. This is a gentle way of getting you to do that without threatening you. You Everybody should get everybody should get 50 out of 50. Okay, enough on that one. The next one is a little bit different. Um, this one is
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Related notes
Summary, takeaways, and chapters were generated by AI from the video's transcript and may contain errors. The video belongs to its creator, Wm_T Evans.