Intek RheoVac 950A - Manual (Page 44)

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I:\OFFICE\WPMANUAL\RV950A Appendix C revB.doc Feb. 4, 2010
To allow for future expansion and up to three different probes, each probe is allocated a space of 100
registers, with the registers for the first probe beginning at address 0101. Registers for the second probe
begin at address 0201, and the third probe begins at register address 0301. Table C2.3 details the
RheoVac Model 950 data register setup when in Multiplier Integer mode.
Table C2.3: Modbus Data Registers (Multiplied Integer Mode)
Address Description Format Read Only?
0101 – 0105 Probe Serial Number 10 ASCII characters Yes
0106 Error Code: see Section C.2.6 16-bit unsigned Yes
0111 Actual Volume Flow 16-bit unsigned Yes
0112 Multiplier Value 16-bit unsigned Yes
0113 Total Mass Flow 16-bit unsigned Yes
0114 Multiplier Value 16-bit unsigned Yes
0115 Water Vapor Flow 16-bit unsigned Yes
0116 Multiplier Value 16-bit unsigned Yes
0117 RheoVac Pressure 16-bit unsigned Yes
0118 Multiplier Value 16-bit unsigned Yes
0119 Water Vapor Specific Volume 16-bit unsigned Yes
0120 Multiplier Value 16-bit unsigned Yes
0121 Water Vapor to Air Mass Ratio 16-bit unsigned Yes
0122 Multiplier Value 16-bit unsigned Yes
0123 Relative Saturation 16-bit unsigned Yes
0124 Multiplier Value 16-bit unsigned Yes
0125 Water Vapor Partial Pressure 16-bit unsigned Yes
0126 Multiplier Value 16-bit unsigned Yes
0127 Air Flow In-Leak 16-bit unsigned Yes
0128 Multiplier Value 16-bit unsigned Yes
0129 Probe Temperature 16-bit unsigned Yes
0130 Multiplier Value 16-bit unsigned Yes
C.2.5 MODBUS DATA REGISTERS (Single Float Mode)
In Single Float mode, all of the data values are converted into the 4-byte, big-endian hexadecimal string
corresponding to their single-precision float representation. The Modbus client program must be capable
of converting these 4-byte values back into single-precision float values. If the client software is unable
to make this conversion, the Multiplied Integer mode must be used. Data in the Single Float mode is
transmitted as follows:
RheoVac Pressure (probe reading) = 1.257
Single-Float Hex Representation = 0x3FA0E560
Register 117 (high word) = 0x3FA0
Register 118 (low word) = 0xE560
As in the Multiplied Integer mode, each probe is allocated a space of 100 registers, with the registers for
the first probe beginning at address 0101. Registers for the second probe begin at address 0201, and the
third probe begins at register address 0301. Table C2.4 details the RheoVac Model 950 data register
setup when in Single Float mode.