TX or RX ist blinking not both

[off99]

Hi ,

I cannot get it to work that both RX and TX Led blinking at the same time! If I Change PIN 16 and 17 the other start to bling. What have I done wrong?

uart:
id: mod_bus
tx_pin: 17
rx_pin: 16
baud_rate: 9600
stop_bits: 1

modbus:
id: modbus1

flow_control_pin: 4 #for use when you use a rs485 board without auto flow control. Like the rs485 max board.

modbus_controller:

• id: ${modbus_controller_id}
  address: 0x1
  modbus_id: modbus1
  setup_priority: -10
  update_interval: 15sec

I am using this TTL :
JZK 5PCS TTL to RS485 module, 485 to serial port UART level mutual conversion, hardware automatic flow control, TTL Turn RS485 3.3V 5V

Thanks
Mit freundlichen