Three weeks into a new PLC programming job with zero PLC experience, no training and nobody nearby to ask. That question drives this episode, along with four more from the plant floor.
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Learn more at Joltek:
- Unmanaged Switches and Cybersecurity:
https://www.joltek.com/blog/industrial-unmanaged-switches-cybersecurity- PLC Lifecycle and Migration:
https://www.joltek.com/blog/rockwell-plc-lifecycle-migration-guide- Industrial Ethernet Reliability:
https://www.joltek.com/blog/industrial-ethernet-reliabilityThe career question is the one worth sitting with. A computer science graduate takes a PLC programmer role, is promised training, gets one day of introduction, then is left alone while the rest of the team sits in another country. Three weeks in, they are asking whether an associate degree in industrial maintenance would have been smarter. My answer is no, and it is not close. Nobody hired that person believing they had ten years of ladder logic behind them. What is missing is not a degree, it is a request. Find the program, price it, say how long it takes and what it lets you do that you cannot do today, and hand your manager a decision that is easy to approve. I went through this at Procter and Gamble. By the time the company sent me to official Rockwell Automation training I knew more than the course covered, because I had been learning RSLogix 500 and Studio 5000 on live projects. The average controls engineer now earns $119,682, up 4.3 percent year over year, and 38 percent of manufacturers name the skilled worker shortage as a top business threat. Leverage sits with the person willing to learn on the job.
The episode opens with a first control panel built by someone four years into filling and capping machines. The layout is good: breakers top left, a 24 volt supply feeding the switch and the controller, wire duct run so the wiring lands clean. Two things stand out. The controller is a Siemens SIMATIC S7-200 Smart, which is obsolete, so the toolchain question is real before a single rung gets written. A current S7-1200 G2 in TIA Portal is a better place to spend learning hours. The five port switch also looks unmanaged, fine on a bench and a problem once that habit reaches a production network.
On why there are so few good PLC tutorials on YouTube, coverage is genuinely thin outside Rockwell Automation and Siemens, and it is not gatekeeping. It is cost. A used PLC or HMI runs a few hundred dollars. A bench that can demonstrate coordinated servo work on Kinetix, Sercos or Siemens drives runs into tens of thousands of dollars and past $100,000. The industry also moves slowly, so a ten year old RSLogix tutorial is still accurate.
The technical highlight is a CANopen motion problem on a Schneider Electric Lexium LXM32 drive. The JOG_LXM32 block will not accept a velocity change while running. MC_MoveVelocity latches velocity only on the rising edge of execute. MC_JOG does accept a live change, but on restart the drive intermittently receives the velocity from the previous move, and synchronous PDO transmission did not fix it. The shipped workaround keeps rewriting the velocity variable with slightly different values so every scan forces a fresh write. Ugly, effective, and the customer accepted it. On the Rockwell side I have solved the same problem by leaving commanded velocity alone and dynamically changing the gear ratio to a virtual axis.
Last is a PanelView 7 Plus that tests clean in FactoryTalk View Studio ME, then loses tags and throws communication errors once downloaded. The poster reports a controller firmware update fixed it. I doubt that is the mechanism. A PanelView 7 Plus talks to controllers as old as a PLC-5. Flashing the controller almost certainly invalidated the shortcut in RSLinx Enterprise, and rebuilding that path is what restored communication. When an HMI works on the desk and fails on the panel, start at the path, not the code.
Timestamps
0:00 Intro
0:20 First control panel build: any advice?
1:45 The S7-200 Smart is obsolete
4:25 Lost three weeks into a new PLC programming job
8:15 Why going back to school is the wrong move
8:50 How to ask your manager for training and get a yes
10:20 Is there a lack of PLC tutorials on YouTube?
14:45 The worst motion control workaround I have seen
15:45 MC_JOG, JOG_LXM32 and the velocity that will not change
18:50 Dynamic gearing as the Rockwell alternative
20:45 PanelView 7 Plus download and communication errors
23:20 Why the RSLinx Enterprise path is the real suspect
25:00 Wrap up
Connect:
LinkedIn: https://www.linkedin.com/in/vladromanov
Joltek: https://www.joltek.com
SolisPLC: https://www.solisplc.com