3. INT201 Connection

INT201 connects a PC to one serial port at a time: the RS232 service port of a LiBat™ BMS for LiMon™, an RS485 line or a 3.3 V or 5 V UART. This page shows the block diagram of the board, the wiring for each mode, the mode switch and the RS485 termination.

3.1 Block Diagram

The USB side and the serial side of the INT201 are isolated from each other; power crosses the barrier through an isolated DC/DC converter and the data through a digital isolator. What the PC sends goes to all three ports, and the mode switch selects the port whose receive line goes back to the PC.

Fig.3.1.1: INT201 Block Diagram

INT201 v1.5 block diagram: on the USB side the USB-C connector, ESD protection and the USB to UART bridge; the isolator and the isolated DC/DC across the 1 kV barrier; on the serial side the SW1 selection of the receive line, the RS232, RS485 and UART ports and connector 3 with ISO 5V

3.2 USB and Power

INT201 takes its power from the USB port of the PC; it needs no other supply. Connect it with a USB Type-C cable (connector 1). The PC shows it as a serial port once the driver is installed (1. Introduction). The data LED (connector 2) blinks while data is sent or received.

Info

The serial side is isolated from USB and the PC (1 kV). ISO GND on connector 3 is the ground of the serial ports, not the ground of the PC.

3.3 Mode Switch

The mode switch SW1 (connector 4) selects the port the INT201 receives from. What the PC sends goes out on all three ports at the same time.

Fig.3.3.1: INT201 Mode Switch Settings

INT201 v1.5 SW1 settings: RS232 mode with both levers OFF, RS485 mode with lever 1 ON, UART mode with lever 2 ON

3.4 Port Connection

Connect the device to connector 3 for the mode set on SW1. For LiMon™, use RS232 mode and the RS232 service port of the BMS; the pins of the service port are on the pinout page of each board.

Fig.3.4.1: INT201 Connections in RS232, RS485 and UART Mode

INT201 v1.5 connector 3: in RS232 mode pins 7 and 6 crossed to the RX and TX of a BMS service port with ISO GND on pin 5; in RS485 mode pin 1 to A and pin 2 to B, pins 4 and 9 linked for 120 ohm at a line end; in UART mode pins 3 and 8 crossed to the RX and TX of the device, pin 5 to GND and pin 10 as an optional 5 V supply

RS485 termination

Link pin 4 to pin 9 of connector 3 only when the INT201 is at an end of the RS485 line; it puts 120 Ω between A and B. Leave the pins open in the middle of a line and in RS232 or UART mode.

Danger

Check every connection and cable before you plug connector 3 into the INT201 or the device.