Average temperature measurement with MPT / RTD
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Instruction manual VITO
Page 31
4.2.2
Additional settings for and 877 FDI
Item
Name
Description
W2
=
Protection level 2
Enter protection level 2
OB
=
Option board *)
Three ASCII characters. This item informs the XPU what option
board is installed. That can be:
MPU : for HCU/ICU option board in MPU emulation mode
HPU : for HCU/ICU option board in HPU emulation mode
EG
=
Enable temperature
One ASCII character; either ‘D’ or ‘E’. With this item can be
transmission *)
selected if the 877 FDI shall answer on a temperature request
(C-record), addressed to the connected level gauge.
E : transmission of temperature record enabled
D : transmission of temperature record disabled
Note:
When item
EG
is set to ‘E’, make sure the related level gauge
has no temperature option installed.
TF
=
Temperature source
One ASCII character; either ‘I’ or ‘E’. this item selects if there is
Selection
a temperature measurement inside the indicator (internal) or to
be fetched from the Enraf field bus (external).
E : Internal
D : External
EX
Exit
Exit protection level 2
*) This item is not implemented in the XPU-2.
4.2.3
Temperature verification MPT
(Multiple Pt100 spots)
probes
After the settings described in section 4.2.1 and, if applicable in section 4.2.2, are entered the temperature
measurement is operational.
The following checks can be made to verify if the settings are made correct and the product temperature reading
is correct.
•
Read item AP (Average Product temperature):
This data item is preceded by four status characters. The first status character is a hexa-decimal number,
indicating the highest selected element for average product temperature calculation. This can be judged,
on basis of the product level, and with the items
U0
–
UF
(calculated spot positions), item
MO
(temperature element offset), item
MP
(product immersion depth) and item
MI
(switch hysteresis).
Refer to figure 4.2:
A spot element will be used in the average product temperature calculation if its position is below the
actual level minus the product immersion depth.
A spot element won’t be used in the average product temperature calculation if it is above the actual level
minus the product immersion depth plus the switch hysteresis.
•
Verify the average product temperature by manual measurement:
Refer to Appendix C for the procedure to verify the average product temperature reading by using a
portable electronic thermometer.
Содержание Enraf VITO
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