Reach with NMEA 0183 multiplexer problem

[Cristobal (Cristobal Valdivieso)]

Hi,

I’m trying to connect the Reach to a NMEA 0183 multiplexer (Actisense NDC-4) with no luck. The multiplexer is supposed to work with differential and single ended devices and I have tested that works fine with other differential devices I have. Also, the multiplexer is specified to work with inputs of 1.8V difference so 3,3V of the Reach should be fine.

I’ve connected Reach Tx to multiplexer A/+ and Reach Ground to multiplexer B/-, and I get just some nonsense characters. I have tried differents baudrates in the Reach and in the multiplexer.

I have performed some tests with an oscilloscope and I can confirm that Reach is sending data with 3.3 V level. The problem (I think) is that when connected to multiplexer, voltage drops to 1.5V that is below the range specified for the multiplexer, also the signal is a lot more noisy .

Any advice would be very appreciated.

[igor.vereninov]

@Cristobal

Actisense NDC-4

I had a quick glance at the manual and it seems to expect RS232 not UART.

[Cristobal (Cristobal Valdivieso)]

Thanks for your answer Igor, but actually Actisense NDC-4 accepts RS232 and multiple variants of NMEA 0183 devices, for different voltage levels and type of connection (single ended or differential). I have contacted Emlid support but in the first instance I don’t receive a very satisfying answer, so I will go back to them.