Series | Appendix E MODBUS Commands |
there is an informal register numbering convention derived from the original (now obsolete) Modicon Modbus protocol specification, and used by many vendors of Modbus capable products.
Registers | Usage | Valid Function Codes | |
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Read/write bits ("coils") | 01 | (read coils) 05 (write single coil) | |
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| 15 | (write multiple coils) |
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02 | (read discrete inputs) | ||
03 | (read holding registers) 04 (read | ||
| ters"), IEEE 754 floating point register | input registers) | |
| pairs, arbitrary length strings encoded as |
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| two ASCII characters per |
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Read/write | 03 | (read holding registers) 06 (write | |
| ters"), IEEE 754 floating point register | single register) 16 (write multiple | |
| pairs, arbitrary length strings encoded as | registers) | |
| two ASCII characters per |
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Each range of register numbers maps to a unique range of ad- dresses that are determined by the function code and the register number. The address is equal to the least significant four digits of the register number minus one, as shown in the following table.
Registers | Function Codes | Data Type and Address Range |
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01, 05, 15 | Read/write bits | |
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02 | ||
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03, 04 | ||
03, 06, 16 | Read/write | |
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Register Definitions
The meter serial number and those variables that are commonly monitored (mass, volume and energy flow rates, total, pressure, temperature, density, viscosity, Reynolds number, and diagnostic variables such as frequency, velocity, gain, amplitude and filter set- ting) are accessible via the Modbus protocol. Long integer and floating point numbers are accessed as pairs of
The flow rate, temperature, pressure, and density variables may be accessed as either the flow meter internal base units or in the
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