Hi,
am trying to establish a Modbus communication. here am using SEALEVEL 7205ec card which is installed in my HMI.
I tried with LOOPBACK adaptor its working fine. when I tried with modscan 32 its throwing up error as Recieved invalid response to MODBUS query **.
am not able to find the solution with it.

 

Since the SEALEVEL 7205ec is a RS-232, RS-422, RS-485 serial interface card, I'll assume you're using Modbus RTU. And since you only mention the SEALEVEL 7205ec and ModScan23, I'll also assume you are trying to communicate from a computer using some type of adapter (USB to RS-232 or USB to RS-485) to the HMI (that has the SEALEVEL 7205ec card installed). Are these assumptions correct?

What is the HMI and are you sure it even supports the Modbus RTU protocol? If so, is the HMI configured as a Modbus RTU Slave? Have you configured the SEALEVEL 7205ec card for the specific physical interface you're using from your PC (e.g. RS-232, RS-422, or RS-485), note that it appears the card has two banks of DIP switches to select the physical interface used. Is your wiring correct, please double-check (note that for RS-485 terms such as A and B are essentially meaningless, so you may need to swap your data signals). Are your communication settings (i.e. baud rate, parity, stop bits, and address) the same in both ModScan and the HMI?

Please provide as much detail as possible on what devices you have, how they are connected, and exactly what you have tried.

 

Since the SEALEVEL 7205ec is a RS-232, RS-422, RS-485 serial interface card, I'll assume you're using Modbus RTU. And since you only mention the SEALEVEL 7205ec and ModScan23, I'll also assume you are trying to communicate from a computer using some type of adapter (USB to RS-232 or USB to RS-485) to the HMI (that has the SEALEVEL 7205ec card installed). Are these assumptions correct?

What is the HMI and are you sure it even supports the Modbus RTU protocol? If so, is the HMI configured as a Modbus RTU Slave? Have you configured the SEALEVEL 7205ec card for the specific physical interface you're using from your PC (e.g. RS-232, RS-422, or RS-485), note that it appears the card has two banks of DIP switches to select the physical interface used. Is your wiring correct, please double-check (note that for RS-485 terms such as A and B are essentially meaningless, so you may need to swap your data signals). Are your communication settings (i.e. baud rate, parity, stop bits, and address) the same in both ModScan and the HMI?

Please provide as much detail as possible on what devices you have, how they are connected, and exactly what you have tried.

Hi,
Thank you very much for the replay.
you are right, Am trying to communicate HMI through USB to RS-232 convertor.
Am sure HMI will support the Modbus RTU Protocol and it's configured as Slave only. with the help of Dip switches i've configured for RS-232. All the communication settings are checked on both the sides. physical hardware connection will be done as per the attachment. all the setting configuration also shown there.