Configuring and Testing the RS-232/485 Serial Port

Understanding the Serial Buffer System

The camera associates two distinct buffers with the serial port: one for transmitting data and one for receiving data. These two buffers are accessed and controlled via a single set of data access properties.

FLIR provides serial port examples in the Spinnaker SDK for our USB3 Vision and GigE Vision cameras, and in the FlyCapture2 SDK for our older generation USB2, Firewire, and older GigE/USB3 cameras.

Using Spinnaker to control the serial port:

The Spinnaker nodes are documented in the online Technical Reference Manual.  For example, if using the Blackfly S, you can find the Serial Port descriptions on our support site here. 

Using Flycapture2 to control the serial port:

The Flycapture2 serial port registers are documented in the Technical Reference Manual, which can be found on the support downloads page for your respective camera.  For example, if using the Blackfly PGE camera, you can find the manuals here.

Serial Port Setup:

To physically wire your serial port to the camera, you need to connect your serial device to the RX/TX/GND pins of the cameras GPIO port.  Refer to the technical refence manuals above for the correct pinout for your camera model.

If connecting the cameras serial port to the PC, which is used for our SDK examples and the walkthrough below, you will need the following setup:

1. Your PC needs a serial port. If one does not already exist, purchase a USB to Serial port cable or adapter.  After installing this, your PC will see a serial port in device manager.  Note the COM port assigned to this serial port.
2. From your PCs serial port, you need a RS232 to TTL converter.
3. To wire up from the RS232-TTL converter to the camera, use a FLIR supplied GPIO cable or make your own from the part numbers supplied in our technical reference manual. Wire up the TX/RX/GND pins between the adapter and the camera.

You now have a serial port connected to the PC.  If you open a terminal window on your PC (hyperterminal, teraterm, putty, etc.), use the example below or our SDK examples to test that the camera is properly sending and receiving serial data.

Serial port example:

Both Flycapture2 and Spinnaker SDKs have serial port example code.  Below is a walk through of the steps to test receiving and transmitting serial data with the camera.  The Flycapture2 registers are mentioned below as they are more complicated, but you can follow the same workflow for the Spinnaker nodes using the below and the Technical Reference manual linked above.

To calculate the base address:

• Query the offset inquiry register (488h).
• Multiple the value by 4. (The value is a 32-bit offset.)
• Remove the 0xF prefix from the result.

Transmitting and Receiving Examples

To configure and test these examples:

• Connect the camera’s serial port to your PC’s serial port. Consult your camera’s Technical Reference for GPIO pin layouts (which pins are designated for RS-232/485) and GPIO electrical characteristics.
• Access the camera’s register space. This can be done by using the FlyCap software included in the FlyCapture SDK. Consult your camera’s Technical Reference for register definitions and individual bit descriptions.
• Access Microsoft’s HyperTerminal program to display the characters received from the camera.

Start-->All Programs-->Accessories-->Communications

Transmit Characters to a PC

This example describes how to send four characters from the camera to the serial port on a PC.

This example uses 0x2000 as the base address. Always query SIO_CONTROL_CSR_INQ register 488h to obtain the correct offset for your camera.

*The actual transmit buffer size may be larger than that reported in step 3 above. When this is the case, the buffer space remaining that is reported in step 8 will not decrease until the actual buffer space remaining is less than 255 bytes.

To send more than four characters either:

• Repeat steps 7 through 9 above, and send characters in sets of four;

Or,

• Do a block write of all the characters using registers 0x2104 – 0x21FF. Consult the FlyCapture API documentation for information on block transfers.

Although both types of writes to the transmit buffer may have to be 32-bit aligned, the number of characters transmitted does not. Subsequent writes to the buffer will overwrite characters that were not transmitted during a previous transmit.

Receive Characters from a PC

This example describes how to send four characters from the PC to the camera’s serial port.

To receive more than four characters either:

• Repeat steps above, and receive characters in sets of four;

Or,

• Do a block read of all the characters using registers 0x2104 – 0x21FF. Consult the FlyCapture API documentation for information on block transfers.

Although both types of reads from the receive buffer may have to be 32-bit aligned, the number of characters received does not. Extra characters read will be filled with 0s.

The actual receive buffer size may be larger than that reported above.

Transmitting and Receiving Data Simultaneously

Simultaneous transmitting and receiving of data can be achieved in a similar way to the examples above. The primary difference is that register 0x2004 must be set to 0xC0000000 to enable both transmit and receive. Once set, transmit and receive transactions are interleaved as required by the application.