Does anyone know if it is possible to set RS485 DB9 port on TWR-SER2 to HDLC/SDLC mode?
Or on the TWR-IND-IO module? We have both and need to get SDLC data in from a sensor.
As you know that RS232 use +/-12 logic to transfer data, so the transceiver which can convert 3.3V logic to +/-12 V logic is required, both the TWR-SER2 and TWR-IND-IO boards have only transceiver circuit or isolated transceiver circuit, which can convert 3.3V logic from UART to +/-12V RS232 logic, whether the HDLC/SDLC protocol is supported or not is dependent on the UART module on MCU.
As you know that the UART uses asynchronous protocol to transfer data, one data transfer consists of START bit, data bits and stop bit, there is not any clock for UART, so it is asynchronous protocol, in other words, if you use UART as physical layer, it is a asynchronous protocol. The HDLC is a higher layer based on UART. all Kinetis processor has at least one on-chip UART module, some has multiple UART modules, it is chip by chip.
Regarding the SLDC, it seems it uses synchronous protocol, pls check your sensor bit pattern to determine if UART can implement it or not.
You can list the part number of your sensor so that we can check if UART can implement it or not.
Pls check the UART chapter for Kinetis family.
this is Kinetis website:
Kinetis Low Power 32-bit ARM Cortex-M MCUs|Freescale
Hope it can help you.
So that means I have to do it in SW? I.e these boards do not support it in H/W?
Yes, you are right, the UART module is physical layer, it only provides data transferring function, the HDLC layer has to be implemented on software, HW does not support HDLC.
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