Which products are affected?
ESP-HMI1-P (HMI Designer V1.1 and higher)
What happens?
Process data telegrams can be accessed in writing and reading mode via variables. Dependent on the data type of the variable (Word, DWord) 2 or 4 bytes of the telegram can be accessed. The position inside the telegram is specified via an offset.
The data of the process data telegrams are copied byte per byte in a mirrored way in the variable of the keypad. This means that the top priority byte of the variable can be found in the byte of the PDO telegram whose position has been defined via the offset.
Example:
If bit 0 has been set in word 1 of the process data telegram via the keypad, the keypad should transmit the following telegram:
01 00 00 00 00 00 00 00 (hex)
However, due to this function restriction the keypad sends the following telegram:
00 01 00 00 00 00 00 00 (hex)
Instead of bit 0 the keypad sets bit 8 (bit 0 in the high priority byte) in the process data telegram.
When does the problem occur?
The response described before occurs if the DEVICE_CAN_MASTER controller has been connected to the CAN port in the Project Manager of the HMI Designer.
The DEVICE_CAN_SLAVE controller is not affected by this function restriction.
Possible diagnostics?
None.
Short-term measures/recommendations?
Use the DEVICE_CAN_SLAVE controller if process data telegrams are to be accessed via the keypad.
The only difference between DEVICE_CAN_SLAVE and DEVICE_CAN_MASTER is that, when using the DEVICE_CAN_SLAVE, the keypad sends a network management telegram (NMT) when being switched on. As a result, the stations connected are put in the Operational CAN status.
Evaluation:
Usually the data between the keypad and the device connected are exchanged via parameter channels. Only the process data communication is affected by this function restriction. The function restriction can be avoided by applying the short-term measure/recommendation mentioned above. The function restriction will be detected during commissioning at the latest.
