Owner manual

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I:\OFFICE\WPMANUAL\RV950A Appendix C revB.doc Feb. 4, 2010
Table C2.4: Modbus Data Registers (Single Float Mode)
Address Description Format Read Only?
101 – 105 Probe Serial Number 10 ASCII characters Yes
106 Error Code: see Section C.2.6 16-bit unsigned Yes
111 – 112 Actual Volume Flow Single-Precision Float Yes
113 – 114 Total Mass Flow Single-Precision Float Yes
115 – 116 Water Vapor Flow Single-Precision Float Yes
117 – 118 RheoVac Pressure Single-Precision Float Yes
119 – 120 Water Vapor Specific Volume Single-Precision Float Yes
121 – 122 Water Vapor to Air Mass Ratio Single-Precision Float Yes
123 – 124 Relative Saturation Single-Precision Float Yes
125 – 126 Water Vapor Partial Pressure Single-Precision Float Yes
127 – 128 Air Flow In-Leak Single-Precision Float Yes
129 – 130 Probe Temperature Single-Precision Float Yes
C.2.6 RHEOVAC INSTRUMENT ERROR CODE
The error code address will return 4 ASCII characters (ASCII Mode) or 2 Hex bytes (RTU Mode) that
represent a binary number. A value of 1 in the binary representation will indicate a specific error
depending on the location of the 1 in the binary number as described in Table C.2.5. Examples are
shown in Table C.2.6.
Table C2.5: Modbus Error Code Decryption Table
Error Indication CalX MSG8 MSG7 MSG6 MSG5 MSG4 MSG3 MSG2 MSG1 MSG0
Binary Value 0 or 1 0 or 1 0 or 1 0 or 1 0 or 1 0 or 1 0 or 1 0 or 1 0 or 1 0 or 1
Table C2.6: Modbus Error Examples
ASCII Mode Output
(data portion only)
RTU Mode Output
(data portion only)
Binary Representation Indicated Error Messages
30 30 30 30 00 00 0000 0000 0000 0000 No errors
30 30 30 31 00 01 0000 0000 0000 0001 MSG0
30 30 34 43 00 4C 0000 0000 0100 1100 MSG6, MSG3, MSG2
30 31 43 41 01 CA 0000 0001 1100 1010 MSG8, MSG7, MSG6, MSG3, MSG1
30 33 30 34 03 04 0000 0011 0000 0100 CalX, MSG8, MSG2
C.2.7 MODIFYING THE MODBUS CONFIGURATION FILE
To modify the configuration file, the RheoVac Model 950 must be attached to a local network. Once
connected, Windows Explorer can be used to browse into the RheoVac Model 950 similar to a PC. Using
the name of the RheoVac Model 950 as the Network ID, the Modbus settings file can be found at the
following location:
\\<NETWORK_ID>\RheoVac\init\serial.ini
Figure C2.1 shows a sample serial.ini file. The Modbus settings are listed under the section titled
“[Modbus]”. In addition, when the Modbus “Mode” setting is 0 (Multiplied Integer), the settings listed
under the “[DecLoc]” section define the decimal location for each of the 10 process variables. These
values can be changed to fit the needs of the existing serial Modbus network. Once the changes have
been made and the file has been saved in its current location, the RheoVac Model 950 must be rebooted