PSoC™ 4 Forum Discussions

Hi,

A pleasant day to you all!

I humbly request for a technical support from this community regarding my cuurent predicament. Attached herewith is my simple implementation of an instrumentation project, using the CY8CKIT-145-40XX PSoC 4 module. It involves voltage measurement (using PSoC4 ADC block) and serial communication. The master controller is a PLC, with RS485 connection. My CY8CKIT-145-40XX is connected to a TTL-to-RS485 converter. This is just a single node point-to-point communication. The sequence is as follows:

1.) PSoc4 will send an initial command string to the PLC (e.g. "ABCD\r"). In return, the PLC will turn on and turn off some relays. After the relay actions, the PLC will send back some string to PSoC4, in which the PSoC4 will send back the acquired readings to the PLC, as a result.

2.) Initially, I used the baud rate of 9600 bps, but I intentionally set it to the lowest acceptable baud rate of the PLC of 1200 bps. This is due to the fact that I am yet currently finding the cause of the miscommunication, and at the same time, I have just a digital multimeter for various signal tracing and measurements.

3.) I implemented the UART block, with RX interrupt. First, with external interrupt to no avail. Lately, I switched to internal interrupt, but the result is the same. The PLC promptly receives the string command coming from PSoC4, and the PLC sends back the command. This is where it is getting weird.

4.) The CY8CKIT-145-40XX cannot be triggered by the incoming serial data from the PLC. But, a voltage disturbance is observed on the kit's pins (P3.0 as RX, P3.1 as TX). This validates that the PLC is indeed sending serial data. However, I observed that the interrupt service routine/handler is somewhat triggered by the transmit action only, and not by the PLC. Whenever the PSoC4 sends out the string, the interrupt is triggered altogether. So, I know that the interrupt handler is working as expected, albeit the RX interrupt from the PLC is not received properly.

5.) I referred to similar problems in this community, but my situation is quite different. And honestly, I even tried some recommendations on some threads (regarding PSoC4 UART RX) to my project, but the result is still the same, RX interrupt cannot be triggered by the PLC. In the past, I have used PSoC5LP and PSoC4 using I2C, and not UART, with no problems at all.

Please find time to check on what I am doing is wrong, or lacking. Your most prompt and positive response will be highly appreciated.

Thanks and Best Regards,

dudeskie

I have added code.

I modified the configuration。

I recompiled the code and the added code was lost. How to set , the code I added is not lost?