ONICON F-2600 - Manual (Page 83)

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F-2600 & F-2700 Vortex Flow Meter Manual 02/15 - 0808-7 / 19204 Page 83
The following four selections are available in this menu. When selecting an item, the
protocol is changed immediately without having to press the ENTER key.
0-1:2-3 Most significant register first, most significant byte first (default)
2-3:0-1 Least significant register first, least significant byte first
1-0:3-2 Most significant register first, least significant byte first
3-2:1-0 Least significant register first, most significant byte first
Table 2. Byte Order
Note that all of the registers are affected by the byte order, including strings and registers
representing 16-bit integers. The register order only affects the order of those registers
representing 32-bit floating point and long integer data, but does not affect single 16-bit
integers or strings.
Modbus Protocol
The Modbus RTU protocol is supported in this implementation. Supported baud rates are
1200, 2400, 4800, 9600, 19200, 38400, 57600, and 115200. The default baud rate is 19200
baud. Depending upon the Modbus protocol selected, data is transmitted in 8-bit data
frames with even or odd parity and 1 stop bit or no parity and 2 or 1 (non-standard) stop
bits.
The current Modbus protocol specification does not define register usage, but there is an
informal register numbering convention derived from the original (now obsolete) Modicon
Modbus protocol specification which is still used by many vendors of Modbus capable
products.
Registers Usage Valid Function Codes
00001–09999 Read/write bits ("coils") 01 (read coils) 05 (write single
coil) 15 (write multiple coils)
10001–19999 Read-only bits ("discrete inputs") 02 (read discrete inputs)
30001–39999 Read-only 16 bit registers ("input
registers"), IEEE 754 floating point
register pairs, arbitrary length strings
encoded as two ASCII characters per
16-bit register 03 (read holding registers) 04
(read input registers)
40001–49999 Read/write 16-bit registers ("holding
registers"), IEEE 754 floating point
register pairs, arbitrary length strings
encoded as two ASCII characters per
16-bit register 03 (read holding registers) 06
(write single register) 16 (write
multiple registers)