What do we mean by trip codes? And what are some of them? 

All opinions are mine and mine alone.

A programmable logic controller (PLC) is found in a commercial or industrial environment. It is typically used to control electromechanical equipment in a complex setting like a manufacturing assembly line or for simple applications, like turning the lights on and off at night or during the day. 

A PLC communication error occurs when the controller does not respond to communication requests or responds negatively to those requests. A PLC communication error can occur between the programmable controller and the devices it controls or when the technician tries to program the device remotely. 

Error codes

Programmable logic controllers are built by several manufacturers and are designed for specific uses. Each company has a series of error codes or known as trip codes, that refer to their specific API. For example, a timeout error can cause a device to not communicate correctly, or a checksum error can be generated when the communication packet is the wrong size. Another communication error can occur when the controller does not respond to the last message request or does not have enough time to respond to the request.

Communications

PLCs can communicate via serial ports with other equipment or by connecting a monitoring device to the RS-232 modem port available on the PLC. A modem connection that is not properly seated in the port can cause a communication error to occur when you try to access the device using a cell phone or other communication device. When connected to a remote monitoring device, a technician can program the PLC from afar, send and receive data, and view PLC logs. Interruptions in the signal will also cause communication errors.

Defective parts

Defective communication cards in a PLC can also cause communication errors. A “receive” or “transmit” error can occur during communications, causing all data received or sent by the controller to be missing. Other communication errors can occur due to faulty communication wiring, or if water enters the communication cable connection points. Each of these types of errors usually requires a visual inspection of the device, none of which can be fixed by accessing the device from a distance.

Software and firmware updates

As with any computer hardware, to avoid communication errors and other problems, the device’s software must be compatible and updated with all other devices with which it interfaces. Setting the device to automatically check for firmware or software updates or to schedule it for updates can prevent communication errors from occurring. Power outages can also affect the controller and may require a restart to reset the communication device and avoid these errors.

Here are some of the trip codes: 

HF01 – SOFTSTARTFAIL: Soft start relay failure detected by DSP (not applicable to SE size 5).

If the inrush/soft start relay opens up while the drive is running or does not close correctly, the drive will trip on HF01.

HF02 – FAILURE: OI trip detected at power up.

If the drive detects an OI.AC (over-current trip on power up), then the drive will trip on HF02 and not OI.AC.

HF03 – FANFAILED: Cooling fan not running (if fitted). No PWM detected by micro.