Siemens MD-BMS - Page 87

Appendices
Appendix B
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MD
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BMS and MD
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BMED Power Meters Modbus Absolute/Net Value Measurement Registers and
Protocol Commands
87
Building Technologies 125-202
06/06/2017
Read Holding Registers
This command reads the contents of a contiguous block of holding registers containing
data values from the power meter. When a read command is received, the power
meter sends a response that includes the value of the requested registers.
Table 24: Format for Modbus Command 03.
Command Information Command Layout Example Command
Power meter address Nn 37
Command number 03 03
First register to read – high order bits xx 00
First register to read – low order bits xx 0C
Number of registers to read – high order bits Xx 00
Number of registers to read – low order bits xx 01
CRC low order bits xx 41
CRC high order bits Xx 9F
Command Example
This command reads from a power meter with an address switch setting of 37 hex,
reading one byte starting at register offset 0C hex. Note that offset 12 corresponds to
Modbus register 40013. All values are hexadecimal.
Table 25: Example for Modbus Command 03.
Example Request Field Name Command
(Hex)
Response Field Name Response
(Hex)
Power meter address 37 Power meter address 37
Command 03 Command 03
Starting register address to read-
high order bits
00 Byte count 02
Starting register address to read-low
order bits
0C Register value-high order bits 00
Number of registers to read – high
order bits
00 Register value – low order bits 00
Number of registers to read – low
order bits
01 CRC low order bits 70
CRC low order bits 41 CRC high order bits 40
CRC high order bits 9F
Command: 3703000C0001419F
Response: 37030200007040