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6.8.1 Conditioning internal references: 'Cond'

WARNING!

Changing the internal references will
alter the instrument performance. Do
not attempt to recalibrate these
references unless you have adequate
test equipment and have read the
following instructions. For routine
calibration of the instrument use the
Trim Menu described in Section 7.

These functions are contained in a protected
sub-menu to minimise the possibility of accidental
adjustment. Select 'Cond' from the menu and press

The transmitter will display '0000'. Using the

and

Down

buttons and the

button to move to the

next digit enter the password 'SurE'. (Note that 'S'
is entered as '5') Pressing

will then give access

to a sub-menu containing the four references.
There is a ten second time-out on entering the
password.

6.8.2 Voltage input reference 'U.IP'

With the BA378C input terminals connected to an
accurate voltage calibrator, select 'U.IP' from the
'Cond' sub-menu and press

The transmitter will

respond by displaying 'Lo' which is a request for an
accurate -75.000mV input. Adjust the external
voltage calibrator to supply -75.00mV and press

to store this figure in permanent memory. The
transmitter will display scrolling decimal points while
the reference is being updated and will then return
to the 'Lo' prompt.

Select 'Hi' from the sub-menu which is a request for
an ac75.000mV input. When the input is
correct press

to store this figure in permanent

memory. The transmitter will display scrolling
decimal points while the reference is being updated
and will then return to the 'Hi' prompt. This
completes adjustment of the voltage input
reference.

6.8.3 3-wire RTD reference '3rtd'

This adjustment, which is only necessary if the
transmitter is used with a three wire resistance
thermometer, should be performed after the
voltage reference has been calibrated. To adjust
the 3-wire RTD reference the resistance
thermometer should be replaced by a 100 ohm
standard resistor or calibrator, with the
compensation loop remaining connected between
terminals 3 and 4. It is preferable to make this
substitution as close to the RTD as possible, but
transmitters may be calibrated in a workshop.

Select '3rtd' from the 'Cond' sub-menu and press

The transmitter will display scrolling decimal points
while the reference is being updated followed by
'Ent' prior to returning to the '3rtd' prompt. This
completes adjustment of this reference.

6.8.4 4-wire RTD reference '4rtd'

This adjustment, which is only necessary if the
transmitter is used with a four wire resistance
thermometer, should be performed after the
voltage reference has been calibrated. To adjust
the 4-wire RTD reference the resistance
thermometer should be replaced by a 100 ohm
standard resistor or calibrator, with both
compensation loops from terminals 1 and 4
connected at the standard resistor or calibrator. It
is preferable to make this substitution as close to
the RTD as possible, but if necessary the
transmitter may be calibrated in a workshop.

Select '4rtd' from the 'Cond' sub-menu and press

The transmitter will display scrolling decimal points
while the reference is being updated followed by
'Ent' prior to returning to the '4rtd' prompt. This
completes adjustment of this reference.

6.8.5 Output current reference 'OP'

Warning: ensure plant safety

before performing this adjustment

This adjustment is only necessary if the transmitter
4/20mA output current is used. A method of
accurately measuring the transmitter output current,
such as a DVM, is required to calibrate this
reference.

Select 'OP' from the 'Cond' sub-menu and press

the transmitter will display 'Sure'. If it is safe to
change the transmitter output current between 4
and 20mA continue by pressing

. The transmitter

will display 'ZEro', pressing

again will change the

display to '.004A' and the transmitter output current
to approximately 4mA.
The transmitter output current shown on the
external current measuring instrument should be
adjusted to 4.000 ±0.001mA using the transmitter

and

Down

buttons. When correct press the

push-button to return to the 'ZEro' prompt.