Siemens Milltronics BW500 Operating Instructions Manual page 141

Device Identifier (R40,064)
This value identifies the Siemens Milltronics device type and is "2" for the BW500 and BW500/L.
Handshaking Area (Parameter Access)
Built into BW500 and BW500/L is an advanced handshaking area that can be used to read and
write 32 bit parameters.
Mapping
Parameter Read and Write (40,090 – 40,095) is a series of six registers that are used for reading
and writing parameter values to and from the BW500 and BW500/L. The first three registers are
always unsigned integers representing parameters and index values. The second three registers
are the format and value(s) of the parameter.
All parameters normally accessed through the hand-held programmer are available through
these registers:
Address
40,090
40,091
40,092
40,093
40,094
40,095
40,096
40,097
Reading Parameters
To read parameters through Modbus follow these steps:
1. Send the parameter, its primary index, and its secondary index (usually 0) and format to
registers 40,090, to 40,093.
2. Wait until you can read the above values from the registers (40,090 to 40,093).
3. Read the value from registers 40,094 and 40,095.
Writing Parameters
To set parameters through Modbus follow these steps:
1. Send the parameter, its primary index, and its secondary index (usually 0) to registers
40,090, 40,091, and 40,092.
2. Write the value to registers 40,096 and 40,097
3. Write the desired format word to register 40,093 to enable the BW500 and BW500/L to
interpret the value correctly.
BW500 and BW500/L
Operating Instructions, 12/2016, A5E33482052-AD
11.5 Modbus RTU/ASCII Protocol
Description
Parameter (integer)
Primary Index (integer)
Secondary Index (integer)
Format word (bit mapped)
Read value, word 1
Read value, word 2
Write value, word 1
Write value, word 2
Communications
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