Holding Registers about arduinomodbusslave

[ysmilda]

When your EEPROM is empty before uploading the full.ino example all the digital pins should be INPUTS. This means that if you read the Input Status this should reflect the current state of the digital pins you defined. To change the pinMode you should write a 0 (input) or a 1 (output) to the corresponding Holding Register.

From your description I'm not completely sure what it is that you're trying to do.

[DpunktS]

yes at the very beginning all PINs were inputs. Then I wanted to write in the holding register. Writing always stops with an error and the next time the holding register was read there were 255 in it and all pins are outputs. how do I get the 255 out of the eeprom.

[yaacov]

This is the loop that read the eeprom
https://github.com/yaacov/ArduinoModbusSlave/blob/master/examples/full/full.ino#L52

This is the line handling CB_WRITE_HOLDING_REGISTERS that changes the pinMode
https://github.com/yaacov/ArduinoModbusSlave/blob/master/examples/full/full.ino#L210

so you can:
a. set the eeprom to what needed before the loop in line 52
b. call the device with modbus write holding register to the address that will change the currect binMode.

[DpunktS]

I have now deleted the EEPROM again so that it is at 0. Nevertheless I cannot write 1 into the EEPROM with QModMaster. Error code: Illegal data value

[ysmilda]

ArduinoModbusSlave/examples/full/full.ino

Line 201 in 4fbc8c1

if (value != INPUT || value != OUTPUT)

This line should have a && instead of a ||. Small logic mistake that breaks this example. I'll make a merge request to fix this.