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naeem1234
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Re: Elevator Algo 2018/08/13 07:18:23 (permalink)
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Thanks for everyone's critical input.. it was very helpful for me for sure. As my job is just of a developer and not a product designer nor the investor so don't have much freedom to select the technically correct approach.. i think the business model of a product is more important to select what technology should be used.. the main target of the investor is not the use of any specific technology but to make his business profitable (at least).
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katela
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Re: Elevator Algo 2018/08/13 08:51:21 (permalink)
+1 (1)
How cheap are cables is your area because this project is supposed to be cheaper and low maintenance, but based on your requirements running lot of wires between floors is going to cost you a fortune depending on your local electrical cabling installation regulation, more wires are prone to faults unlike a system with few wires. So in long term your system might require frequent maintenance and might not be reliable.
Remember safety is also very important it can not be bypassed by cost.
As Jorge suggested in #5, I think multiple small MCUs interconnected by some kind of bus might be cheaper then running lot of wires between floors, unless cables are really very cheap in your area.
You must remember of voltage drop in your design as well, so the longer the cable the more voltage drop, you'll have to use thicker cables witch won't be cheap as well. 
This approach will also be less prone to problems and fixing problems might take less time unlike dealing with a bunch of wires.
An RS485 or CAN bus can be considered 
You have to explain to your contractor all the possibilities before deciding on this proposed solution.
 

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Jim Nickerson
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Re: Elevator Algo 2018/08/13 09:10:44 (permalink)
+1 (1)
If you deliver what the customer asked for it is more likely you will get paid what you asked for.
Despite what might be the technically better approach.
Elevators have been running with discrete wiring for quite some time.
What incoming voltage is used for these discrete inputs ? 
#23
JorgeF
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Re: Elevator Algo 2018/08/13 10:04:06 (permalink)
+1 (1)
Hi
naeem1234 
Once the whole system is installed and operational then very little chance of problem occurring in (1), but all the remaining components (2), (3) and (4) will have day to day or maybe once in a week or month type of problem arrival rate specially where the elevators are used very roughly.. for which a simple electrician would suffice to attend and fix the problem without even using a multimeter. So the cost of technician as well as the cost of tools and replaceable components is very important here. Also because the elevator is in use all the time so the time-to-bring-it-back-to-operational is also very important and in this case where most of the faults can be seen by visible eyes they can also be fixed very quickly.
 
Last year, in a residential building, we changed the maintenance provider for a set of 2 elevators because during one year we acumulated a total of 14 days out of service spread by the 2 elevators, with the worst case beeing one elevator stopped for 2 days in a row. Plus a few quicks with the pannels, signaling and buttons.
 
naeem1234  
Only in the case when something would go wrong in the controller box (1) only then some high cost will be incurred.. specially the visit of an engineer to the site etc.

Nop.
If something goes wrong with the controler, its replaced in-site by the same low-cost electrician and then an engineer might, or not, take care of it at the shop. Probably a new controler will be cheaper than the time of the engenier.
Anyhow, if the controler is well designed it will probably be trashed in less than 10 years, still in perfect operating conditions. Just because some wireless infrastructure has become so cheaper than cables and connectors that can fail.

Best regards
Jorge
 
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#24
naeem1234
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Re: Elevator Algo 2018/08/13 11:27:21 (permalink)
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JANickerson
What incoming voltage is used for these discrete inputs ? 




The wiring is mostly 24V DC.. and on the PCB there are Opto-isolators that are connected to the GPIO pins. There are some relays in the schematics which i am not sure how they are used.
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JorgeF
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Re: Elevator Algo 2018/08/13 11:46:14 (permalink)
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Hi
naeem1234
JANickerson
What incoming voltage is used for these discrete inputs ? 

The wiring is mostly 24V DC.. and on the PCB there are Opto-isolators that are connected to the GPIO pins. There are some relays in the schematics which i am not sure how they are used.

Besides beeing 24V, its probably that all communications, since signaling to lights or motor control, is based on 20mA loops. Those relays may be there just for that, open and close the loop.
Its a commom way of interfacing the 20mA loops with voltage based electronics.

Best regards
Jorge
 
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naeem1234
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Re: Elevator Algo 2018/08/13 11:48:51 (permalink)
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katela
How cheap are cables is your area because this project is supposed to be cheaper and low maintenance, but based on your requirements running lot of wires between floors is going to cost you a fortune depending on your local electrical cabling installation regulation, more wires are prone to faults unlike a system with few wires.



No idea about the cable prices.. but i have seen lots of wiring bundles at the contractors godown. One thing regarding wiring is that mostly when hi-rise buildings are constructed then at that time they lay down so many wirings for security alarms, cctv, intercoms, hvac, electric supply etc so i think its at that time that the elevator wiring is also put in the building design.. so those extra elevator wires don't seem to be a bulk cost in the overall wiring.
 
Also since the discrete wiring is just carrying 24V DC signals so no special guage or specs need to be fulfilled which would have to be in the case of wiring for any specific bus like ethernet etc. So i think the cheapest available electrical conductor wire maybe a mix of copper and aluminium etc would be enough to carry a 24V DC signal.. and even a voltage drop of few volts would not do much harm to the signal and its detection.
 
This is just my approximate ideas.. the things on ground may not be as i have estimated about them.
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Jim Nickerson
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Re: Elevator Algo 2018/08/13 11:57:15 (permalink)
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Do I understand the controller PCB already exists and you are writing the software for it ?
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du00000001
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Re: Elevator Algo 2018/08/13 12:01:21 (permalink)
+1 (1)
Copper isn't cheap - nowhere in the world.
Mixing it with aluminum results in "real disaster". Aluminum alone isn't better.
And to have a minimum of reliability, you need a minimum of cross-section - irrespective of any voltage drops (that depend on current vs. cross-section and should be negligible for inputs).
Outputs are somewhat different, but if it's only about some LED(s) it really doesn't matter.
 
What really is an issue: the stability of the cable attached to the cabin. This one is exposed to significant mechanical loading  (its own weight) plus continuous bending. More or less a "life-cycle test" for the wiring harness.
 
But obviously all recommendations are fruitless.
 
BTW: where are you located? India? Somewhere else in SE Asia?

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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Jim Nickerson
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Re: Elevator Algo 2018/08/13 12:04:47 (permalink)
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Many companies have been making "Travelling Cables" for quite some time.
https://www.google.com/se...id=chrome&ie=UTF-8
#30
naeem1234
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Re: Elevator Algo 2018/08/13 12:29:57 (permalink)
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JANickerson
Do I understand the controller PCB already exists and you are writing the software for it ?




We are using the schematic of an existing Controller as starting point. I think all the interfacing and wiring will remain the same and we will change the MCU and then have it programmed as per our own logic. The original controller is using some TI controller.
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NKurzman
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Re: Elevator Algo 2018/08/13 12:41:18 (permalink)
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You can use several CPUs connected via CAN, SPI, I2C RS-485, ect.  Or using peripheral I/O IC chips.  Better will be determined but, time , skill, space, Budget, ect. 
#32
naeem1234
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Re: Elevator Algo 2018/08/13 12:50:09 (permalink)
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JorgeF
Just because some wireless infrastructure has become so cheaper than cables and connectors that can fail.




A very interesting future option. Can you suggest any available wireless modules that can work for this purpose (vertical tunnel like area of elevator with moving cabin inside, maximum 12 storey building approx. 50m height, data rate very low, signal reliability very good)
post edited by naeem1234 - 2018/08/13 12:55:21
#33
qɥb
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Re: Elevator Algo 2018/08/13 13:10:25 (permalink)
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malaugh
...
Microchip chip sell a part https://www.microchip.com/wwwproducts/en/MCP23S17  that expands to 16 I/O.  You can just daisy chain these together to get as many I/O as you require.  You can also use a simpler chip like the 74HC595 for output, and a equivalent (cannot remember the part number) for input.
...

You could just refer back to post#2 ;)
 

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du00000001
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Re: Elevator Algo 2018/08/13 13:23:28 (permalink)
+1 (1)
@ Jim Nickerson
Exempt the additional pairs of .5 mm^2, the wires are 0,75 mm^2. That's a lot of copper for LEDs and buttons.
 
@ Naeem1234
50 m with free line of sight should be easily bridged per WiFi. Uo to 30 m might even be bridges by BT.
But how to supply the cabin? A battery system might work, but reliiable automatic charging might become a challenge.

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
#35
JorgeF
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Re: Elevator Algo 2018/08/13 14:41:34 (permalink)
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Hi
du00000001
@ Naeem1234
50 m with free line of sight should be easily bridged per WiFi. Uo to 30 m might even be bridges by BT.
But how to supply the cabin? A battery system might work, but reliiable automatic charging might become a challenge.

The cabins have power, and all electromecanics are on the outside, only the panels (LED and buttons) are inside.
 
As for a solution for wireless comms in such an environment, a mesh network with dinamic routing might do the trick.
 

Best regards
Jorge
 
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#36
NKurzman
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Re: Elevator Algo 2018/08/13 15:02:31 (permalink)
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Wi-fi would be a science Project. There is a Lot of Metal in an elevator shaft including a moving Car.  Wi-Fi on the various floors The Possibility of Transmitters on the Roof.  And a dozen Smart phones in the car looking for an AP.  I would choose RS-485 or CAN.  But since that is not what the Person paying the Bills wants, it is not what they are going to pay for.  Sometimes people want low tech, because low tech people can fix it.  Maybe version in Version 2. IF Version 1 works and is not over budget.
And half the wires do not move.  The Floor buttons and lights are fixed.
#37
Aussie Susan
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Re: Elevator Algo 2018/08/13 19:17:41 (permalink)
+2 (2)
Seriously - do yourself a favour and say now and/or find another customer.
All that will happen is that you will get the blame/bad reputation from the job.
I have said "no" to a client in the past and ended up with a ton more work when I explained why and gained their respect for being a 'partner' and not just a mercenary contractor.
Susan
#38
PStechPaul
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Re: Elevator Algo 2018/08/14 02:42:34 (permalink)
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It might be worthwhile to consider fiber optic cable for connections. I found some that seem to be designed for the purpose:
 
https://www.alibaba.com/p...List.50.1fdb58174d7D4B
 

 

 
#39
naeem1234
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Re: Elevator Algo 2018/08/14 13:40:36 (permalink)
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Can you give any suggestion how to represent the firmware flow for an Elevator Controller in the form of any diagram or flow chart or state diagram etc as there are so many inputs and outputs? Any link to sample for quick start would be very helpful. 
#40
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