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connecting_external_devices [2018/07/10 10:35]
akuzmuk created
connecting_external_devices [2018/07/11 09:40]
akuzmuk [Connection Diagnostics]
Line 46: Line 46:
 As for the 2-wire circuit of the isolated RS-485, it is also unstable for the following reason. The system can be under parasitic induction in this case, but the current noise "​general form" always eager to go back to the source, no matter where and how the chain captures interference,​ ie, including return through an isolated "​general"​ scheme. This point can in turn become a source of electromagnetic interference for another part of the electronic circuit (for example, through capacitive parasitic links). A large explanation of the role of one wire is given only to save the user from the loss of valuable time for setting up communications. In addition, on long lines and at high exchange rates, it is recommended to use a matched cable (twisted pair on the screen, 120 ohm impedance) and termination resistors at the ends of the network segment. As for the 2-wire circuit of the isolated RS-485, it is also unstable for the following reason. The system can be under parasitic induction in this case, but the current noise "​general form" always eager to go back to the source, no matter where and how the chain captures interference,​ ie, including return through an isolated "​general"​ scheme. This point can in turn become a source of electromagnetic interference for another part of the electronic circuit (for example, through capacitive parasitic links). A large explanation of the role of one wire is given only to save the user from the loss of valuable time for setting up communications. In addition, on long lines and at high exchange rates, it is recommended to use a matched cable (twisted pair on the screen, 120 ohm impedance) and termination resistors at the ends of the network segment.
  
-===== Connection ​Diagnostics ​=====+===== Connection ​diagnostics ​=====
 First of all, after connecting the device and creating a connection, you can create a register in a known state, for example, the bit "​always on", etc. After the register is created, its value (Value) will be displayed with the register list:  First of all, after connecting the device and creating a connection, you can create a register in a known state, for example, the bit "​always on", etc. After the register is created, its value (Value) will be displayed with the register list: 
  
-{{ ::​read-error.png?​direct&​600 |}}+{{ ::​read-error.png?​direct&​912 |}}
  
-A dash line instead of value means that there is no connection. ​If there appears, ​first check the cable and the settings on both sides again+A dash line instead of value means that there is no connection ​establishedIn this case first double ​check the cable and the settings on both sides. Cables are sources of issues in most cases.
  
-To deal with communication issues on the built-in RS-485 port TX/RX LEDs on the front panel will help with diagnostic - during ​normal operation they should flash alternately. ​+To deal with communication issues on the built-in RS-485 port TX/RX LEDs on the front panel could be used. During ​normal operation they should flash alternately. At first blinks TX LED and then blinks RX LED.
  
-In the absence of RX it is clear that the device does not respond at all, i.e. the format or speed of the exchange may be incorrectly configured+In the absence of RX blinks ​it is clear that the device does not respond at all, i.e. the format or speed of the exchange may be misconfigured. Or there is issue with wires.
  
-If the RX LED flashes in an irregular manner, as if "​breaking through" ​through ​a uniform flashing TX is likely to be in the presence of strong electromagnetic interference,​ it is necessary to follow the recommendations for RS-485 connection. ​+If the RX LED flashes in an irregular manner, as if "​breaking through"​ a uniform flashing TX is likely to be in the presence of strong electromagnetic interference,​ it is necessary to follow the recommendations for RS-485 connection. ​
  
 If the value is read but incorrect - the wrong data type is specified in the register description,​ so for example only the parameter byte can be read instead of the whole word. If the value is read but incorrect - the wrong data type is specified in the register description,​ so for example only the parameter byte can be read instead of the whole word.
  

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