2.4 Resolving Software Issues

Basics

For communication to work correctly, both devices must have identical software settings. For instance, if the baud rate is 2400 on the controlled device, it must also be 2400 on the control system.

Other parameters that must be the same are data bits, parity bits, and stop bits. 

  • Data bits are the number of bits per single character transmitted. This number should be between 7 and 8. 

  • Parity bits define whether the number of 1's during one-byte of transmission is odd or even. They should be set so that all transmission is either odd or even. If the receiver doesn't care about parity, it can be set to 0. 

  • Stop bits end the transmission of the data. The number can be 0, 1, or 2.

Standard settings for these parameters for most AV devices are: 8, None, and 1 respectively (also referred to as "8 n 1").

You should know the following terms:

  • Baud Rate
  • Data Bits
  • Parity Bits
  • RS-232
  • Stop Bits

Troubleshooting IP to serial connection

In a  typical system, the control system sends a command to a device over RS-232 and gets feedback from the device over RS-232.

In a networked environment, the control system controls devices via the Internet so an IP to RS-232 cable would be used.

Image Credits: httTroubleps://aveosystems.com/troubleshooting-rs-232-connections/

When the control system tries to connect to a device over the network, it opens a communication path, sends a command, and depending on the equipment, expects a response from the device to verify the connection to the equipment. If it doesn't connect, it will send a “connection failed” message. If it does connect, you should receive a message or icon indicating that the connection was successful.

If you are using an IP-to-serial interface to connect to the equipment’s serial port over the network and there is more than one IP-to-serial interface in your system, confirm that you are working with the correct IP-to-serial device. Ensure the control system has a network route to the IP-to-serial interface. This is the same requirement when communicating between any devices over a network. If the control system can’t reach the equipment over the network, you won’t be able to control it.

If it is unable to connect, there are two options: 1) troubleshoot the network connection, or 2) troubleshoot the serial connection. For detailed directions, review the article Troubleshooting RS232 Connections in the Resources.

There are software products built for checking and debugging connections. The one pictured below is Serial Port Debugger. This software allows you to check both the controller and the device.

Courtesy of: https://www.com-port-monitoring.com/serial-port-troubleshooting/

Here are additional resources you may find useful:

Complete the following task or self-assessment:

Work through the process of troubleshooting a USB to serial connection and an IP to serial connection.