Grossel
Well-Known Member
Hi - sorry if posted on wrong forum, but I didn't find any that fit.
Where I work, we have some master modules capable of comunicating with modbus/rs485 sensors. So far so good. That is made by a well-known manufacturer.
However - the master module have a RS485 port physically compatible with any ethernet cable around. This is also pretty useful.
However, there is something really stupid by design (in my mind at least) and I have questioned this but not got any good arguments from the manufacturer on why this is.
So, any cat5e cable have this standard layout of four pairs. Therefore, when designing the RS485 connector and pinouts - one should assume the plus and minus of RS485 is arranged in such a way that it takes advantages of a standard cat5 cable to avoid cross talk, by ensuring the plus and minus is assigned to the same pair of wires.
However, this is not the case - the plus and minus in RS485 on these devices are assigned to a different wire pair when using a standard cat5e cable, and thus not being as effective as possible for long distance + high baud rate ; that is without me have to replace the RJ45 connector in order to get the plus and minus on the same wire pair.
My question is - What reasons would a manufacturer of signal processing devices have to make the pinout of RS232/RJ45 socket that is not compatible with the standard of what to be assumed being the most used network cable on the marked ?
Where I work, we have some master modules capable of comunicating with modbus/rs485 sensors. So far so good. That is made by a well-known manufacturer.
However - the master module have a RS485 port physically compatible with any ethernet cable around. This is also pretty useful.
However, there is something really stupid by design (in my mind at least) and I have questioned this but not got any good arguments from the manufacturer on why this is.
So, any cat5e cable have this standard layout of four pairs. Therefore, when designing the RS485 connector and pinouts - one should assume the plus and minus of RS485 is arranged in such a way that it takes advantages of a standard cat5 cable to avoid cross talk, by ensuring the plus and minus is assigned to the same pair of wires.
However, this is not the case - the plus and minus in RS485 on these devices are assigned to a different wire pair when using a standard cat5e cable, and thus not being as effective as possible for long distance + high baud rate ; that is without me have to replace the RJ45 connector in order to get the plus and minus on the same wire pair.
My question is - What reasons would a manufacturer of signal processing devices have to make the pinout of RS232/RJ45 socket that is not compatible with the standard of what to be assumed being the most used network cable on the marked ?
