jraef
Member
My counter to these arguments, and by the way yours a is VERY common opinion so I'm not picking on you specifically, this is a wider issue that you have happened to articulate well from your perspective. So please take it as an open discussion, not a criticism:
1. What is it that you can "troubleshoot" on an analog input and 2wire or 3wire command control signal to a drive? The drive is or is not being told to run, the drive is or is not getting the correct analog value. All of that info is going to be on the display of a networked drive as well. Then there is this new wrinkle; with modern arc flash rules etc., the troubleshooting of those hard wired signals must be done with the proper PPE, which in many cases will be the full blown "bunny suit" with the face shield, arc resistant gloves and boots, maybe even the balaclava and flame resistant underwear. So what really happens is that Relay Joe, who says "I've been doing this for 25 years without this silly suit" does his hard wired troubleshooting with his meter, but not the right arc flash PPE. This risks not only his life and health, but that of the entire company. If there is an accident, OSHA can shut the place down and any supervisor who allowed it can be put in JAIL for not insisting on his following the rules, or not having rules for him to follow. All of the unfortunate other employees, who had zero involvement in this, go home without a paycheck until OSHA is satisfied that this has been fixed and will not happen again. Being able to access and troubleshoot the drive via a network connection in a different room cannot get any safer from an arc flash protection standard. If the drive is off f the network for some reason, and you ate using a managed network such as EtherNet, the network will tell you almost exactly where the loss of communications is taking place so the bunny suit time can be avoided or at least kept to a barenminimum.
2. If the losses from your process being shut down for a day is not worth the cost of spare drives, at least of each frame size to act as emergency donors, then this argument is invalid. If the losses are worth that cost, but the bean counters refuse to include it in their cost of doing business, then they should be fired. Relying on the ability to swap out any drive with any other brand that is on the shelf somewhere is maybe expeditious, but utlimately self defeating in the long run, unless maybe you are a mobile business and cannot drag all of your spare parts around with you (trailer mounted machinery for example). What happens is that you end up with a plant that has 12 to 15 different drive mfrs installed, and nobody has the time or memory to be trained on any of them, so whenever one goes down nobody knows what might be wrong so the ONLY remaining strategy becomes replacement with yet ANOTHER unknown product and the spiral downward into chaos perpetuates itself.
3. Analog is never going away... No, but neither is networking of equipment, especially non-proprietary networks like EtherNet. In fact that is growing, while hard wired connectivity is shrinking, both rapidly.
The generation of technicians coming into the work force now is VERY used to networked devices, but get very little exposure to analog control any more. At the same time, "electricians" are no longer getting the same depth of control troubleshooting experience they once did, I know because I teach classes on VFDs to electricians, it's shocking how little they know now. Getting a license is now mostly about knowing all of the complexities of the NEC, it's too much for them to also learn more specific things, so all they get is OJT, mostly using the "sink or swim" method, because companies have little patience (or budget) for what is considered non-productive work. That knowledge gap will therefore only continue getting further apart. The future will be the electricians pulling wire in conduit and connecting it to switchgear and MCCs while meeting, and keeping up with, the NEC, but the day to day maintenance will need to be done by qualified technicians, whether there is a network or not. Those guys and gals will be fewer in number however, so they will not have the time or patience to track down the reason for a bad analg signal, they will want to walk up to a screen, see the failure and have the network tell them exactly where the problem lies.
As to the "meter vs laptop" issue, also spurious. If you have a network controlling your drives, you must have a controller. If you have a controller, you have access to everything inside of that drive via the network (if it was set up correctly). If you have networked devices, a network and a controller, but get cheap at the end and don't put in an HMI or an Engineering Work Station PC on that network, well then that is just being penny wise and pound foolish...
Please notice, the term OEM is not in the above, because this is not being driven by OEMs or even SIs, it is being driven by end users, and because OEMs and SIs ultimately must serve end users, they are adapting now to try to stick to one strategy rather that try to support multiple versions of everything. Get on board or stand aside and wave goodbye ...
Last edited:
