Andon lights
Andon lights
(OP)
I have been assigned the task of hooking up Andon lights on several machines and departments. I need to have two strobes one for maintenance and one for inspector. I am considering using a plc to track there state potentially so the system could be monitored at a central location. What is the longest I can run the sensors back to a central plc. Or would it make sense to have a plc in each department. Most of our machines are all relay logic and 120vac. Any sensors I would add I was planning on makeing 24vdc for safety and reliablity. Any other ideas would be appreaciated.





RE: Andon lights
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Voltage mode sensors (0-10V for example) are going to be less immune to noise and the distance you can go depends on how noisy the environment is and the shielding on your cable.
You can also get sensors with a serial communication output. Specs for the distance these can travel will be in the datasheet.
Hope that helps.
Jim
RE: Andon lights
Are the lights you are planning to install, going to be hardwired to a selector switch, or do you plan to use PLC I/O?
In the case of hardwired lights, you could use a set of relay contacts wired back to a PLC input. This would also work in the case of a PLC output driving the light, you could bring a signal back to another PLC.
Discrete I/O can go fairly long distances, so you must just have all the lights controlled by one central PLC.
A series of small distributed PLC's all networked together is still another option.
Do you have existing PLC's and I/O available? I can think of a lot of ways to do this, do you want to try to use any existing hardware, or should this be kept separate?
RE: Andon lights
A few of the machines have Horner PLC's with availble io space. I have considered using several small plc's as well. My issue is most of the machines are controlled by relays. Almost all of my plc's are ethernet enabled which would make this very easy however that is the exception to most of my machines on the shop floor.
One of my biggest concerns is today I am just monitoring lights tomorrow I may be monitoring the individual machines for rate and parts counters. I just want to make sure I have a system that is expandable.
RE: Andon lights
Depending on how many machines you have and their proximity to each other, a single PLC might easily handle all your needs.
It would be much cleaner to have all your monitoring on a single small PLC, and not have to mess with the existing programs and relays.
RE: Andon lights
What type of central location monitoring are you considering?
RE: Andon lights