ONICON F-2600 - Manual (Page 82)

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F-2600 & F-2700 Vortex Flow Meter Manual 02/15 - 0808-7 / 19204 Page 82
4.2.2 Menu Items
The following menu items are in the Output Menu and allow selection and control of the
Modbus communication protocol.
Address
When the Modbus protocol is selected, the Modbus address is equal to the user's
programmable device address if it is in the range 1…247 in accordance with the Modbus
specification. If the device address is zero or is greater than 247, then the Modbus address
is internally set to 1.
Comm Protocol
The Comm Protocol menu allows selection of “Modbus RTU Even,” “Modbus RTU Odd,”
or “Modbus RTU None2,” or “Modbus RTU None1,” (non-standard Modbus) with Even,
Odd and None referring to the parity selection. When even or odd parity is selected, the
unit is configured for 8 data bits, 1 parity bit and 1 stop bit; with no parity, the number of
stop bits is 1 (non-standard) or 2. When changing the protocol, the change is made as soon
as the Enter key is pressed.
Modbus Units
The Modbus Units menu is to control which units, where applicable, the meter’s variables
will be displayed in. Internal – (these are the base units of the meter, °F, psia, lbm/sec , ft3/
sec, Btu/sec , lbm/ft3 Display) – variables are displayed in user selected display unit.
Modbus Order
The byte order within registers and the order in which multiple registers containing
floating point or long integer data are transmitted may be changed with this menu item.
According to the Modbus specification, the most significant byte of a register is transmitted
first, followed by the least significant byte. The Modbus specification does not prescribe
the order in which registers are transmitted when multiple registers represent values
longer than 16 bits. Using this menu item, the word order and byte order for floating point
and long integer values may be reversed to accommodate different Modbus operating
systems.