Overview

Use this article when serial commands sent through a Just Add Power device do not control the connected source or display, or when expected serial feedback is not received.

Serial communication depends on the entire path between the control system and the endpoint device. Troubleshoot the path in order: network communication, device identification, serial mode, communication settings, command format, and physical cabling.

Before You Begin

Collect the following information before troubleshooting:

• The IP address of the Just Add Power device connected to the endpoint.
• The serial method being used: Passive, Direct, or API.
• The endpoint manufacturer's serial command and required communication settings.
• The required cable pinout, including whether the connection is straight-through or crossover.
• Whether two-way serial feedback is required.

If the device IP address or network access requirements are unknown, see How to Access a Device and How to Locate a Device IP Address.

Troubleshooting

1. Confirm Network Communication

The control system must be able to reach the Just Add Power device before it can send serial commands through the network.

1. From a computer on the same Data Network as the control system, open the webUI of the target Just Add Power device.
2. If the webUI does not open, confirm the device IP address and the route between the Data Network and the Just Add Power Network.
3. Confirm that the port required by the selected serial method is available:
   • Direct: TCP port 6752
   • API through Telnet CLI: TCP port 23
   • HTTP API: TCP port 80

For routing requirements and configuration options, see Setup a Static Route for an Established Just Add Power System.

2. Confirm the Target Device

Confirm that the command is being sent to the Just Add Power device physically connected to the intended source or display.

1. Compare the target IP address with the Encoder or Decoder inventory in the system report.
2. Open the device webUI and compare its model and network information with the expected device.
3. If physical confirmation is needed, reboot the device through Telnet or its webUI. Observe which device restarts or which video path is interrupted to confirm that the targeted IP address belongs to the intended device.
4. Trace the serial cable from the Just Add Power device to the endpoint and confirm that it reaches the correct serial port.

3. Confirm the Serial Method and Mode

The configured serial mode must match the method used by the control system.

Method	2G Series Name	Command Path	Feedback
Passive	Type 1	Serial enters one device and follows the active Encoder-to-Decoder connection.	Two-way
Direct	Type 2	The control system opens a TCP connection to the device on port 6752.	Two-way
API (CLI Access)	Type 3	The control system sends a CLI or HTTP API command to the device.	One-way

Open the device webUI and confirm that its serial mode matches the control method. The setting location varies by device generation and firmware.

If the application requires a response from the endpoint, use Passive or Direct mode. API mode does not return serial feedback from the endpoint device.

4. Confirm the Communication Settings

Match all serial communication settings to the endpoint manufacturer's requirements:

• Baud rate
• Data bits
• Parity
• Stop bits

For Passive mode, the control system, Encoder, Decoder, and endpoint must use matching communication settings. For Direct or API mode, the target Just Add Power device must match the endpoint.

Do not assume that 9600 8-N-1 is correct. Verify the required values in the endpoint manufacturer's serial-control documentation.

5. Confirm the Command and Format

Verify the command against the documentation for the exact endpoint model. Products from the same manufacturer may use different command sets.

• Confirm whether the command is ASCII or hexadecimal.
• Confirm whether letters are case-sensitive.
• Include the required command terminator, such as carriage return, line feed, or both.
• Confirm that the control system is sending the intended bytes and is not sending the visible characters used to represent a hexadecimal value.
• Confirm whether the endpoint must be enabled for external or serial control.

When using CLI Access or the HTTP API /command/cli endpoint, the serial output can be written with:

stty BAUDRATE -F /dev/ttyS0;printf "SERIAL_CODE_HERE" > /dev/ttyS0

6. Confirm the Pinout and Cabling

RS232 connector pinouts are not universal. A cable can fit both devices and still have the wrong transmit, receive, or ground connections.

1. Compare the Just Add Power serial-port pinout with the endpoint manufacturer's pinout.
2. Confirm that transmit on one device connects to receive on the other and that signal ground is connected.
3. Confirm whether the application requires a straight-through or crossover cable.
4. If the Just Add Power model has a null modem jumper, confirm its position. Move the jumper only after verifying that the current pinout does not match the endpoint.
5. Inspect adapters and field-terminated connectors for incorrect pin assignments, loose conductors, or damaged contacts.
6. Replace the serial cable with a known-working cable of the correct pinout.

When supported, the null modem jumper changes the transmit and receive orientation. It does not correct an incorrect ground connection, an incompatible connector pinout, or a damaged cable.

7. Isolate the Failure

Use a computer with a USB-to-serial adapter and a serial-monitoring application such as PuTTY or Docklight Scripting to determine which part of the communication path is failing.

Test the Endpoint Directly

1. Disconnect the serial cable from the Just Add Power device.
2. Connect the computer to the endpoint using the correct adapter and cable pinout.
3. Configure the serial-monitoring application with the required communication settings.
4. Send the known command, including the required terminator.

If the endpoint does not respond during a direct test, correct the endpoint settings, command, or cabling before continuing.

Monitor the Just Add Power Output

1. Connect the serial output of the Just Add Power device to the computer using the correct adapter and cable pinout.
2. Send the command from the control system.
3. Compare the received bytes with the known-working command, including its terminator.

• If no data is received, recheck network access, the target IP address, serial mode, and control-system connection.
• If incorrect data is received, recheck ASCII or hexadecimal formatting and the command terminator.
• If the correct data is received but the endpoint does not respond, recheck the cable pinout, endpoint serial settings, and endpoint configuration.

Before Contacting Support

Record the following information if the issue remains:

• Just Add Power model, firmware version, IP address, and serial mode
• Endpoint manufacturer and model
• Baud rate, data bits, parity, and stop bits
• Exact command and whether it is ASCII or hexadecimal
• Required command terminator
• Cable pinout and null modem jumper position, if applicable
• Results of the direct endpoint test and Just Add Power output-monitoring test