Yokogawa EJX115A - Manual (Page 45)

<7. In-Process Operation>
7-4
IM 01C25T04-01EN
7.4 Write lock (Write-protect)
function
The transmitter is provided with a write lock (write-
protect) function to restrict write operations to
blocks and prevent inadvertent writing of parameter
data. To enable this function, use the write lock
switch (Hard W Lock) or the WRITE_LOCKING
(Physical block index 34) (Soft W Lock).
The CPU assembly of the transmitter is provided
with a write lock switch (switch 2 in Figure 7.3).
Setting switch 2 to On activates the write lock
function.
When the write lock switch is disabled, set 0
(protected) for WRITE_LOCKING (index 34) of the
physical block to enable the write lock function.
• Procedure to call up the display
DTM Physical Block → Configulation → Write
Locking →
EDD [Menu] → Device → Write Locking →
→ On Write lock enabled
→ Off Write lock disabled
These parameters and issue shall control the
parameter access as defined in Table 7.5.
Table 7.5 Access protection
HARDWARE_WRITE_
PROTECTION
WRITE_LOCKING
Remote
access
possible
0 (unprotected) 2457 (unprotected) YES
— 0 (protected) NO
2 (protected, no manual
operation permitted)
— NO
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Amplifier Assembly
SIMULATE_ENABLE switch 1
2
O
N
O
N
"ON" : Write lock enable
WRITE LOCK
Figure 7.3 Write lock Switch
7.5 Local Operation Interface
WARNING
The local operation switch on LCD must not
be used in the hazardous area. When it is
necessary to use the switch, operate it in a non-
hazardous location.
IMPORTANT
Do not turn off the power to the transmitter
immediately after performing parameter setting.
Powering off within 30 seconds of performing
this procedure will return the parameter to its
previous setting.
The zero point can be adjusted and the Ident
number and Bus address can be set by using
the push button below the LCD display and the
adjustment screw on the main body. Before the
setting, check the following items at the Local
Operation Interface.
• The Write Locking (WRITE_LOCKING)
parameter and the hardware write lock switch
are both turned off and disabled. For the
procedure, see Chapter 7.4. When the Write
Locking (WRITE_LOCKING) parameter is
enabled, the key mark appears on the LCD
display, which indicates that no settings can be
made except for zero point adjustment.
• The Local Operation (LOCAL_OP_ENA)
parameter is enabled.
• The TEST screen is disabled.
• Communication is set to aperiodic. Even during
periodic communication, zero point adjustment
is possible.
• The degree of adjustment depends on the
speed of turning the adjustment screw. Turn the
screw slowly for fine tuning and turn the screw
fast for quick tuning.
External Adjustment
screw cover
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Figure 7.4 External Adjustment Screw