I have a customer that has a machine and given the age and relay logic. The relays are failing. Looks like a box full of cotton candy. My question is do i replace the control buttons with new ones when I install the PLC or should I install an HMI instead ?
HMI or NOT
- Thread starter ktmtragic
- Start date
It is really subjective. I'm not sure what the control buttons are, but you will most certainly want a hard-wired E-Stop button as well as a start cycle and stop cycle button. They should be able to start and stop the machine without the HMI if necessary.
With an HMI you can do things that are not possible or difficult to achieve with just buttons and lamps.
Change setpoints.
See analog values.
See timer values.
Change timer setpoints.
Display alarms with detailed alarm description.
Display detailed sequence information.
And you can simplify the hardware by removing redundant buttons and lamps.
But most important, by changing from hardwired relay logic and hardwired user interface to what is essentially software, you can standardise on a control concept where you maintain and improve the software gradually over time, so that you get a much BETTER control system. And there are goodies. You can have remote diagnostics for example. And an alarm system that logs the alarms and other stuff so you can see what has been going on.
But it will cost more in the short run.
Change setpoints.
See analog values.
See timer values.
Change timer setpoints.
Display alarms with detailed alarm description.
Display detailed sequence information.
And you can simplify the hardware by removing redundant buttons and lamps.
But most important, by changing from hardwired relay logic and hardwired user interface to what is essentially software, you can standardise on a control concept where you maintain and improve the software gradually over time, so that you get a much BETTER control system. And there are goodies. You can have remote diagnostics for example. And an alarm system that logs the alarms and other stuff so you can see what has been going on.
But it will cost more in the short run.
janner_10
Lifetime Supporting Member
As Jesper said IMO, HMI is the way to go, all those relays and push buttons is just archaic.
Noting wrong with have the E-Stop reset from the HMI along with the start stop buttons either.
You only need the actual E-Stop as a physical button.
Noting wrong with have the E-Stop reset from the HMI along with the start stop buttons either.
You only need the actual E-Stop as a physical button.
RET
Member
Ask them this question...if the HMI goes out can they wait a few days to run the machine while getting it replaced? If not then replace the buttons.
Well, all of this really depends on how many buttons they have. Say they have 12 buttons and contact blocks. This can easily be $900-1100 dollars worth of just buttons and contact blocks. If you can get an HMI in there and eliminate the majority of it, then it becomes very clear which is more cost-effective.
I'm just a fan of having some kind of manual by-pass in most situations. I have had to go back through and put too many manual by-passes in while waiting on a new HMI to not do it from the start.
Most generally though an ES, Start/Stop and perhaps cycle reset button would be all you needed as they would only be temporary until an HMI could be delivered and installed.
I'm just a fan of having some kind of manual by-pass in most situations. I have had to go back through and put too many manual by-passes in while waiting on a new HMI to not do it from the start.
Most generally though an ES, Start/Stop and perhaps cycle reset button would be all you needed as they would only be temporary until an HMI could be delivered and installed.
The only concern is if this a food grade bowl chopper then does it require a pressure-hose proof HMI or other expensive protection for the screen during the wash-down after use ? Some bowl choppers require local control for loading , raising an acoustic hood and raising the main cover as well as E-stops and start/stop .
I use Weintek HMIs.
7 inch costs $283 plus shipping from here.
http://www.fractioni.com/inc/sdetail/218/35863
10 inch is only $350 plus shipping.
http://www.fractioni.com/inc/sdetail/218/38337
Software is free and they will talk to just about anything.
http://www.weintek.com/globalw/Software/EasyBuilderPro.aspx
For these prices I usually keep a couple of both sizes on hand.
Performance wise they are very fast with a ton of features.
7 inch costs $283 plus shipping from here.
http://www.fractioni.com/inc/sdetail/218/35863
10 inch is only $350 plus shipping.
http://www.fractioni.com/inc/sdetail/218/38337
Software is free and they will talk to just about anything.
http://www.weintek.com/globalw/Software/EasyBuilderPro.aspx
For these prices I usually keep a couple of both sizes on hand.
Performance wise they are very fast with a ton of features.
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