User`s manual

MGate 4101-MB-PBS UM Quick Configuration

A-6

Integrate Modbus Serial and Ethernet with Gateways

Ordinarily, Modbus TCP and Modbus ASCII/RTU are unable to communicate with each other.

However, with a Modbus gateway in between the Modbus serial network and the Modbus Ethernet network, TCP

masters are able to communicate with serial slaves and serial masters are able to communicate with TCP

slaves.

Diagnose Packet Format

When the communication of MGate works well between PROFIBUS and Modbus protocols, MGate won’t go into

diagnostic mode. However, if there is an error in the Modbus connection, for example, a disconnection or no

responses, the MGate will continue to send polling requests until three requests are sent without response.

Then, it will enter diagnostic mode. In this mode, the MGate will send diagnose packets periodically. Upon

receiving the correct response, MGate will go back to normal operations.

Refer to the diagnose packet format table to help identify why the MGate entered diagnostic mode.

Byte Parameter Notes

1 Length The length of diagnose packet

2 Page number The paging number which the problem data

locates

3 Module The PROFIBUS IO module number which the

problem data locates

For instance, if the diagnose packet is 03 01 03, that means the problem data is located on the third PROFIBUS

IO module in page one. Using this information, you can check if the location of the internal memory is correct.