4.5.10. Serial port

Controller allows control through UART serial port with TTL 3.3 V logic. UART outputs are located on BPC connector. Because of widespread availability of UART and adapters to USB, Bluetooth, Ethernet and other standard interfaces there is an option for wireless control (Bluetooth) or control over the internet (Ethernet). UART data protocol is the same as USB data protocol. I.e. it is enough to enable nonstandard serial port polling in XiLab or in libximc and the device will be found if response delay doesn't exceed two seconds. It is also possible to control controller with the help of other independently programmed micro-controller, however in this case it will be required to support controller communication protocol.

UART supports the following settings.

Transfer rate 9600-921600 bit/sec
Data bits 8
Parity enabled or disabled
Parity type even, odd, space, mark
Stop bits 1 or 2

Note. To connect to the controller via UART one should first connect to it via USB and set required speed, parity and stop bits and then save settings to non-volatile memory. Standard settings are listed in Communication protocol specification, use them if you cannot connect.

Logic type TTL 3.3V
Maximum data transfer speed 921 kbit
Nominal output current 5 mA

Output and input parameters

Connection diagram

WARNING. High data transfer speeds through long cables in case of electromagnetic interference are impossible. If transfer errors do occur, use RC filtering circuits and reduce transfer speeds so that characteristic time of an RC-circuit is at least 4 times less than time needed to transfer a single bit. RC-circuit characteristic time is chosen based on the circumstances.

Controller board

For the controller board UART outputs are located on the BPC connector.

Recommended scheme of connection to serial port pins for the controller board

One-axis and two-axis systems

Among two box versions, only the two-axis system has UART outputs. Corresponding contacts for each axis output on the HDB-26 connector.

Recommended scheme of connection to serial port pins for two-axis system

Multi-axis system

Multi-axis system does not have serial port outputs.

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