Siemens Milltronics BW500 Operating Lnstructions page 116

Error Handling
Errors can be divided up into two general sources:
1. an error in transmission
2. user tries to do something that is not a valid action
In the first case, the BW500 and BW500/L will not respond and let the master wait for a
'response time out' error, which will cause the master to re-send the message.
In the second case, it depends on what the user tries to do. Listed below are various
actions and what the expected outcome is. In general, BW500 and BW500/L will not give
an error to the user request.
• If the user reads an invalid parameter, the user will get a number back.
• If the user writes an invalid parameter (a non-existing parameter or a read only
parameter), the value will be ignored and no error response will be made. However,
the current value will not reflect the desired new value.
• If the user writes a read only register, then the value will be ignored and no error
response will be made. However, the current value will not reflect the desired new
value.
• If the user attempts to write one or more registers that are out of range, an
exception response code 2 will be generated.
• If using an unsupported function code, undocumented results may occur. The user
is encouraged not to do this.
Page 110 Milltronics BW500 and BW500/L - OPERATING INSTRUCTIONS 7ML19985DK05