It's obvious that if the drops are long and are not twisted then you also have more chance to induce noise. While it goes against conventional wisdom, and can potentially cause a problem with circulating currents by grounding a shielded cable at both ends, this method is very effective at keeping induced lightening noise away from the communications lines. Unlike the standard RS232 protocol, RS485 allows many communicating parties to share the same 3-wire communications cable. But some of the other interfaces are certainly interesting because they can be used in situations where RS232 is not appropriate. Although the maximum standard baud rate of the primary serial port is 19200 baud, nonstandard baud rates of over 80 Kbaud can be attained by the 68HC11's on-chip UART and the onboard RS232 driver. In fact, the program works the same as it did before, but now it is using the secondary serial port instead of the primary port -- and you didn’t even have to recompile the code! We have been using Microcontroller Development Boards like Arduino, Raspberry Pi, NodeMCU, ESP8266, MSP430, etc. for a long time now in our small projects where most of the times distance between the sensors and board is not more than few centimeters at max and at these distances, the communication between the different sensor modules, relays, actuators, and controllers can be easily done over simple jumper wires without us being worried about the signal distortion in the medium and the Electrical noises creeping into it.

Other times you may write something and read it back to verify. The load presented by other devices on the network affects this floating so the resistor values may need to be changed depending on the number of devices installed and the values of the pull up/down resistors they are using. A number of vendors have a range of pull up/down resistors installed and allow you to change the selection using software or jumpers. This device and/or the pull up/down resistors of other devices are candidates for investigation. The simplest way of knowing if this is a factor Does the device work properly when it is the only device on the network ? ReflectionsWithout a scope and expertise, you won't know this is a factor. I think you may be able to add a few more devices and still have a fully operational network depending on the load presented by the terminating resistors. The other devices will think that it is transmitting or receiving and thus blocking the line. When a device drives the line it sees the load presented by the other devices and the terminating (and biasing) resistors.

If the vendor did a poor job, what is rs485 cable the default is to have the resistor active and they must be disabled unless they are the terminating devices on the network. Some devices have terminating resistors built into them. If a device floats out of the specified range then to other devices it will look like the floating devices isn't floating at all. When a device wants to send it must grab the line. The RS485 network must be designed as one line with multiple drops, not as a star. In areas with a lot of signal interference, the software may need to perform multiple inquiries to get a valid response. ● No communication, no response. To ensure frame integrity during the transmission, the time interval between two frames must be at least the transmission time of 3.5 characters, and the time interval between two consecutive characters must be no more than the transmission time of 1.5 characters. Line Drive On / OffTo use two wires for RS485 each devices transmitter and receiver must be set to an idle state to release the line for others use.

To use two wires ( as opposed to full duplex 4 wire) for RS485 each devices transmitter and receiver must be set to an idle state to release the line for others use. I don't see a problem the wire I use has 2 wires and a shielding which is the ground. They use the digi xtend wireless modems, which are specifically made to be universal, per the manufacturers website (which I take to mean they probably use asynchronous serial communication). SenseCAP Data Logger and IoT Platform Compatible: Convert to a SenseCAP LoRaWAN® sensor with SenseCAP Data Logger and take advantage of quick and easy set-up in just 5 minutes with SenseCAP Mate APP. 10. Take care with the topology. The best topology is a single trunk that in-outs on the terminal blocks of each device it connects. In unicast mode, the master will initiate a request to a single slave with a specific address.