I determined by measuring water flow that I lost about 50% of my filling flow while the pump was running, so I figured it would be best to not fill while the pump was running at all. After having defined the type of instrument best suited to the needs, if the measurement is performed by indirect insertion, the accessories of the measuring system, such as current and voltage transformers must be chosen with care. 0.2 is the minimum recommended voltage difference that receivers use to detect a change in polarity. I purchased another Pi (I use them all over the place for various projects) and laid out what I wanted it to do. My water temp sensor floats around my pool and my level sensor is nowhere near a power source, so I had to use battery-powered wireless equipment. One of the main reasons why this standard is used it's because wireless rs485 is able to send data a long distance.

Apart from a one-to-one connection, RS485 can be used with a serial bus that connects to multiple peripherals. It enables communication between multiple devices, such as sensors, controllers, and actuators, using the RS485 standard. I am using minimalmodbus to communicate with a PID controller (Love 16C-3) via RS485 using a USB-RS485 adapter cable. 6. Cost-effectiveness - RS485 is typically less expensive(long-distance transmission) than other protocols, making it a cost-effective solution for many applications.7. It can operate reliably over distances of up to 1.2 kilometers (about 4,000 feet) or more, making it suitable for applications requiring communication across large areas. Another potential problem with large networks without isolation, is that severe damage can occur to your entire system, if a high voltage source is connected (accidentally or otherwise) to your communications lines. The voltage level on the Tx/Rx conductors are measured relative to this voltage level. In my case, I just had a simple question: Are you running?

In this case, I had a very easy way to do this. So I needed a way to monitor the power from my pump and figure out if it were running or not. While my pump was running, if I was attempting to fill the pool, I would be fighting the pressure of the pump. The one-way valve prevents pressure from the pump from pushing water against the sprinkler valve when the pump is in operation. I also added a smart meter which I can read in real time to show me that water is flowing and how much water over time I have been using. In theatre and performance venues, what is rs485 cable RS-485 networks are used to control lighting and other systems using the DMX512 protocol. Differences between Modbus and JBUS at that time (number of entities, server stations) are now irrelevant as this protocol almost disappeared with the April PLC series, which AEG Schneider Automation bought in 1994 and then made obsolete. This ensures that all security-related information and incidents are transmitted quickly and with high reliability. The main reason behind using these Ethernet Cables over normal wires is that they provide much better protection against noise creeping in and distortion of the signal over high distances.

I ended up using four of them in my project: one for the water level, one for the temperature of the water and two in the main system to monitor a combination of internal enclosure temperature, filter pressure and water usage. In this mode, a Modbus transaction includes two messages: one request from the master and one reply from the slave. 7uA in deep sleep mode which means they would last a very, very long time on two AA batteries. I used the Sainsmart solid state relays (very inexpensive) in optically isolated mode where I have a separate power input powering the relays as opposed to using the 5v or 3.3v VCC from the Pi. On the other hand, the secondary serial port (Serial2) is implemented using hardware pins PA3 (input) and PA4 (output), and is controlled by the associated interrupts IC4/OC5 and OC4, respectively. Thus, the master has only one input, MISO, which is the slave’s only output. Simple enough. However, I didn't want to run the transformer 24x7 for no reason, so I used a relay to 1) turn on the transformer and then 2) take the 24VAC output from the transformer and connect it to the sprinkler valve.