Bronkhorst FlowDDE - Manual (Page 8)

BRONKHORST ®
3 PARAMETER INFORMATION
FLOW-BUS is used for parameter value exchange between instruments and operation modules (keyboard or PC-
interface). Parameter information consists of several properties for behaviour within the FLOW-BUS system. In the
‘parameter properties’ table you will find a list of parameters and their properties. In the ‘parameter values’ table, the
values are described more detailed. This list consists mostly of parameters for mode settings.
Property description in parameter properties table
Item Description
Parameter(DDE) Unique parameter number (also used for DDE-communication: P(x)).
Name
Name of the parameter, used for parameter identification.
Process Process where parameter is used on FLOW-BUS module, used for communication directly through
RS232. When empty in the table, the process has to be determined from the FLOW-BUS system
information (for parameters located in more than one process, e.g. setpoint, measure).
FBnr(parameter) Parameter number in process on FLOW-BUS module, used for communication directly through
RS232.
Type Variable type of the parameter
• c (unsigned) char 1 byte value 0..255 when StrLen is 0
• c string Multiple bytes when StrLen is other than 0
• i (unsigned) integer 2 bytes value 0..65535
• f float 4 bytes value +-1.18E-38..+-3.39E+38 (IEEE-floating point notation)
• l (unsigned) long 4 bytes value 0..4294967295
data types > 1 byte are MSB first.
StrLen Length of string in bytes (characters) used in combination with Type c for strings
• -2 indicates that a string is zero-terminated, not defined in length, but until the first 0-char.
• X indicates a string with a length of X bytes
• 0 means no info required (not a string type parameter)
Min Minimum value of parameter allowed when parameter is read/written. The value will be checked
on this limit (error when out of limit).
Max Maximum value of parameter allowed when parameter is read/written. The value will be checked
on this limit (error when out of limit).
Read Indication if parameter is allowed to be read via FLOW-BUS.
Write Indication if parameter is allowed to be written via FLOW-BUS.
Poll Indication if parameter should be polled continuously by FlowDDE in order to keep the (changing)
parameter value up to date.
Advanced Indication if parameter is for advanced users only. These are mainly parameters for
maintenance/service.
Secured Indication if parameter is secured for use through FLOW-BUS. Reading this parameter is possible,
but changing it needs special handling.
High security Indication if parameter is highly secured (only few parameters). Reading this parameter is possible,
but changing it needs special handling.
Description Short description about the meaning of parameter or where it is used for.
DDE str Parameter DDE string (max. 10 characters). This becomes the DDE value when parameter is not
available on instrument. Also: until FlowDDE V4.58 used for parameter identification.
Changing parameter values is possible when a parameter is not read-only and not secured. The range
and type of parameters are described in the tables. When parameter values are out of range they will
be either 'clipped' on the nearest value allowed or you will get an error message: 'parameter value
error'.
(FlowDDE) Parameter numbers:
All parameter information is referenced to the parameter number. This is a unique number for a parameter to avoid
redundancy. These numbers are needed for DDE communication only.
For communication with FLOW-BUS through other ways than DDE, directly via RS232 ASCII-strings or via C-libraries,
use the parameter numbers for the FLOW-BUS modules (in column FBnr of Parameter properties table). Also you will
Page 8
FlowDDE 9.17.067