![]() ![]() ![]() It's would be an educated guess these are holding registers, accessed by Modbus function code 03. The Modbus map is not public information (must be requested from the supplier) but the example pseudo code on page 70 shows battery voltage is at hex address 0405 and its a single register. Change the wires on one end to see if such is the case. The good news is reversing the connections does not damage the drivers, it just doesn't work. The bad news is that the assignment or labeling of the (+)/(-) or A/B RS-485 terminals is arbitrary with the result that sometimes (Data +) from one end gets connected to (Data -) on the other end and there's no communication. So you need to make the baud rate and the parity the same on both the master and the slave. I would try no parity first and make sure that the master is set for 8 data bits. The spec for the comm ports (in section 3.10) says the 485 port is half duplex (2 wire + common). Apparently it takes some software to change the settings (maybe even to see them?) The DSE-7300 operator manual shows setting the Modbus slave address and the baud rate on page 70 (pdf). ![]()
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