molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL
© 1998-2007 DH Instruments, a Fluke Company
Page 70
3.4.8
[MOLBLOC]
PURPOSE
To initialize and/or rapidly identify a molbloc that is connected to molbox RFM.
PRINCIPLE
molblocs carry an EEPROM on which are stored the molbloc identification header, molbloc
specific flow calibration coefficients and the zero offset of the molbloc platinum resistance
thermometers. molbox RFM must have this information to accurately identify the molbloc to
which it is connected and to correctly calculate flow through the molbloc. molbox RFM does
not continuously read the information off the molbloc EEPROM. It reads and loads the
information on the molbloc EEPROM each time it powers up. However, if the molbloc
connected to the molbox is changed without turning the molbox RFM OFF and back ON, the
new molbloc and the previous molbloc’s calibration information will continue to be used.
The
[molbloc]
function key provides a rapid and simple way of causing the molbox RFM to
load the molbloc to which it is connected and display a summary of its characteristics. This is
useful when changing molblocs or to identify the molbloc that is currently in service.
More complete molbloc information, including a list of gases for which the molbloc has
specific calibration coefficients, can be accessed by pressing [SETUP] and selecting
<4molbloc> (see Section 3.5.4).
OPERATION
Press the
[molbloc]
function key at any time from the main run screen. molbox RFM will
take a moment to read the molbox EEPROM and then display a summary of the molbloc
identification header including range designation, serial number and calibration date. This
screen is displayed for 5 seconds before operation returns to the main run screen.
If molbox RFM is unable to establish communications
with a molbloc, the display is:
molbloc not detected
ENTER searches again
Pressing [ESCAPE] returns to the run screen. Pressing [ENTER] repeats the molbloc search
just as if [molbloc] had been pressed again.
There is a risk of corrupting the molbloc EEPROM information when molbloc to molbox
RFM electrical connections are made with the molbox RFM power ON. The recommended
procedure is to power OFF the molbox RFM when making and breaking molbloc
electrical connections. The SOFT POWER OFF does not remove power from the
molbloc cable, so the power cord must be disconnected to power OFF the molbox RFM.
3.4.8.1
molbloc-L AND molbloc-S SIZE AND RANGE
DESIGNATIONS
Until mid-1999, molbloc-L elements (molbloc-S was not available at the time) were
always identified by “Range”. The molbloc-L “Range” is the molbloc’s nominal full
scale flow in Nitrogen (N2) at an operating pressure of 250 kPa absolute. Actual
molbloc ranges change with the molbloc pressure dependent calibration type and
gas (see Section 1.2.4.1.2). Since mid-1999, in addition to nominal range, molbloc-L
elements have been designated by size with a sizing code (see Table 13).
On molbloc-L EEPROMs, the molbloc is still identified by its nominal range rather
than by its size. The identification of the molbloc displayed by
[SETUP]
,
<4molbloc>
identifies molbloc-L by both its nominal range and sizing code.
molbloc-L size and range designation correspondence are given in Table 13.
