June-5th-2019, 08:17 AM
Hello Lukas,
this indeed a typo in the link you referenced: https://www.netiot.shop/epages/es767660....s/1322.011.
An RS-485 interface alone can never ever be full-duplex. There is always just a single transmitter that is able to drive the RS-485 bus while all the others a listening. For me it seems that this text was copied 1:1 from the RS-232 module where full duplex is indeed supported. I will let this change today. I am sorry for this inconvenience.
A full duplex version would be indeed a pair of RS-485 interfaces usually named as RS-422 which we don't offer.
You analysed the RS-485 quite well and you looked to the schematics also. And there is indeed a pin that is switching the bus driver between transmit and receive mode and this pin needs to be controlled by the application. So today the only chance you have is to pull the GPIO before sending and to release it after sending. In the example we provided here https://github.com/HilscherAutomation/ne...npix-rs485 as a container we did that using a Node-RED application that takes control of the pin.
I agree that if you don't have any chance to intervene the serial stream and to take control of the GPIO, you can't get your application running since "nobody" is switching between transmit and receive mode. I also agree that in this case a driver is necessary. Just let me re-check the development team what they can do for us to provide such a driver.
I will be back to you.
Thx
Armin
this indeed a typo in the link you referenced: https://www.netiot.shop/epages/es767660....s/1322.011.
An RS-485 interface alone can never ever be full-duplex. There is always just a single transmitter that is able to drive the RS-485 bus while all the others a listening. For me it seems that this text was copied 1:1 from the RS-232 module where full duplex is indeed supported. I will let this change today. I am sorry for this inconvenience.
A full duplex version would be indeed a pair of RS-485 interfaces usually named as RS-422 which we don't offer.
You analysed the RS-485 quite well and you looked to the schematics also. And there is indeed a pin that is switching the bus driver between transmit and receive mode and this pin needs to be controlled by the application. So today the only chance you have is to pull the GPIO before sending and to release it after sending. In the example we provided here https://github.com/HilscherAutomation/ne...npix-rs485 as a container we did that using a Node-RED application that takes control of the pin.
I agree that if you don't have any chance to intervene the serial stream and to take control of the GPIO, you can't get your application running since "nobody" is switching between transmit and receive mode. I also agree that in this case a driver is necessary. Just let me re-check the development team what they can do for us to provide such a driver.
I will be back to you.
Thx
Armin
„You never fail until you stop trying.“, Albert Einstein (1879 - 1955)
