Smart rope


Joined Jan 27, 2019
Since LoRa consumes much less power than Wifi, it can be operated continuously using only solar cells. The solar cell and transmitter module are attached to a pole, and a rod with a pressure sensor is strapped along a wire.
View attachment 295540
If the wire breaks, the altitude at which the sensor is installed will drop, and this change in air pressure is monitored by the server. You can use myDevices Cayenne as a dashboard or use IFTTT to alert you.
The cost of LoRa at each node is prohibitive. Something like a simple 433MHz link to a LoRa gateway might be more affordable, but even then, the costs are very high and the maintenance is nightmarish.


Joined Jan 27, 2019
So how about using Zigbee? Modules made by EBYTE can be obtained cheaply.
Why use Zigbee? The EBYTE modules may be cheap by some standards but they are not as cheap as simple 433MHz options. There will need to be a lot of these in operation. While a mesh network is an attractive idea, it also requires a lot more engineering that a simple hub and spokes arrangement.


Joined Jan 27, 2019
My understanding of the eruv is that the wire isn't fixed to the poles but passes over a support. Could you monitor several sections with one LoRa unit so giving a zone where the problem is?
It passes over because it must, it is attached when it must be as well. Usually it is attached so that it will remain over the lechis or other supports to keep it kosher. So, they must pass over but for practical reasons they are almost always fixed to the thing they pass over.

The issue the monitor is dealing with is the question “is the eruv kosher?” The trouble with this is that the monitoring system can’t really tell, it can only alarm if some condition that could mean that is detected. No single sensor can answer the question and in critical times—right before the start of the sabbath or a festival observance—a false alarm can cause chaos.

Given a very large budget and a competent technical staff, this could probably be done. However from a rubber-meets-the-road practical engineering perspective I really don‘t believe that we can overcome the fundamental problems which are not technical, per se, but social (no unlimited budget, differing opinions on how to approach the entire topic of eruvin, etc.)

Practically, there are some companies that specialize in building and maintaining, and most importantly repairing eruvin. These companies have staff members that are not Jews to allow them to work on the sabbath and sabbath-like observed festival days. They can autonomously repair a downed eruv even on shabbat, so if there were such a contractor engaged it might make sense to monitor even right before the start of it.

I think a very large community with the will to do it could engineer and maintain an electronically monitored eruv. But the design (which is surely possible) would be very extensive, expensive, and complex. In the case of sufficient budget and manpower, LoRa would be an excellent candidate.

In fact, leveraging the same technology applied to smart meters would make a lot of sense. Checking each aspect of the eruv that must be correct would be a matter of choosing a strategy and applying a sensor to each item needing surveillance. This could surely be done, but not in some simple and cheap way.

A weak surveillance system is worse than none since manual checking must be done anyway, and false alarms or unwarranted reliance on no alarms would no doubt lead to turning it off in the former case and reducing the integrity of the eruv in the latter.


Joined May 20, 2021
Incorporating an energy harvesting module into the edge node would further complicate the system. Nevertheless, if you choose to use battery power to reduce the unit cost of the edge node, you will have to go up to the pole every year to change the batteries.

If you think a wireless system is too expensive, then send sensor data via a wired system such as RS232 or RS485. However, someone must always monitor its power and signal lines to ensure that they are not disconnected.

Ultimately, how much money is spent to build the system will determine maintenance costs.

Eruv is boundaries that enclose an area, and if we ignore the cost aspect, they are highly compatible with a mesh network using Zigbee. E18-MS1PA2-PCB is priced at 5.20USD on AliExpress. The wireless standard is a mass of patented technology, and I personally think this module price is surprisingly low.
Last edited:


Joined Jan 30, 2016
In fact, leveraging the same technology applied to smart meters would make a lot of sense. Checking each aspect of the eruv that must be correct would be a matter of choosing a strategy and applying a sensor to each item needing surveillance. This could surely be done, but not in some simple and cheap way
I had the same thought. A UK company I follow, Cyanconnode, are world leaders in bulk smart-meter technology with a very low cost low speed wide area mesh. They've shipped & installed over 30million, iirc, units on the Indian subcontinent and their transceiver is a couple of dollars I believe though it would still need the solar panel/batteries/energy harvester module...


Joined May 20, 2021
I would consider a scarecrow with an HMC5883L in each hand. By freely moving the arms with pillow balls, a single module could monitor wires in two directions at the same time.


Joined Dec 13, 2021
Hi, Yaakov

Thanks for responding so quickly.
The ropes in this case don’t actually do anything. They are there for religious reasons. Most Orthodox Jewish areas have them. They are typically nylon fishing string attached to metal poles about 50-100 feet apart strung about 10-20 feet above the ground.

if the string tears or the alignment changes such that the rope is sagging substantially, it is not “kosher” for the sabbath.

I live in NJ, but if this works, I would like to use it also by my parents in Florida, so the weather can run from snow to hurricane

thanks again. Please send your thoughts
can you send us a few pictures and / or links to the sort of installations your referring to please


Joined Jan 23, 2018
OK, there is indeed a system that could do the monitoring effectively and reliably but it is by no means simple nor cheap.That would be for each of the support elements to have a small retro-reflrctor on the top, near the attachment point, and then for each an industrial laser photo-switch that would detect when the reflector moved out of position. These would need to be the "smart" variety that can use a common bus connection so that any failure point will have a unique identification. Thus the monitor would be at one point.

A second option would be to use a fiber optic cable with connectors spaced along it so that any damage would disconnect rather than damage. That would provide a single notification of failure to initiate a search and repair operation. It is probably the simplest and most applicable scheme available. And possibly the least costly, although it will not be cheap. Fiber optic cables can operate over several kilometers, and so it might possibly just require one receiver and sender. But certainly it could provide an OK/NOT OK signal.
I have no ideas as to if fiber optic cable can be Kosher, or made to be Kosher. That discovery will need to be made by others.
And I was not aware of this Orthodox tradition, pardon my lack of knowledge.
Last edited: