Yokogawa Wireless Temperature Transmitter YTA510 - Manual (Page 30)

3. OPERATION
IM 01C50T01-01E 3-17
1. Call up the “HART output” display. [1.Device
setup
→
4.Detailed setup
→
3.Output condition
→
2.HART output]
2. Select “4. Burst option”. Select a set of data to be
sent.
3. Return to “HART output” display and select “3.
Burst mode”. Select “On” to start the burst option.
Press
SEND[F2] to send the setting. To release the
burst mode, select “Off” in this display.
If the transmitter is equipped with the integral indica-
tor, the LCD displays “B.M.”
3.5.10 Multi Drop
“Multi dropping” transmitters refers to the connection
of several transmitters to a single communication
transmission line. Up to 15 transmitters can be con-
nected when set in the multidrop mode. To activate
multi drop communication, the transmitter address
must be changed to a number from 1 to 15. This
change deactivates the 4 to 20 mA analog output,
sending it to 4mA . The alarm current is also disabled.
● Setting of Multi drop
Call up the “HART output” display. [1.Device
setup
→
4.Detailed setup
→
3.Output condition
→
2.HART output]
Select “1. Poll addr” and set the polling address.(a
number from 1 to 15).
Press
SEND[F2] to send the setting.
If the transmitter is equipped with the integral indica-
tor, the LCD displays “M.D.” and "F.O."
NOTE
1. When the identical address is set for two or
more transmitters in multidrop mode, commu-
nication with these transmitters is disabled.
2. Multi drop mode and Burst mode should not
be operated together at the same time.
● Releasing the Multidrop mode
First, call up the “HART output” display. [1.Device
setup
→
4.Detailed setup
→
3.Output condition
→
2.HART output]
Select “1. Poll addr” and set the polling address to
“0”. Press
SEND[F2] .
3.5.11 Sensor Matching Function
This function is available only when optional specifica-
tion /CM1 is specified with YTA310 or YTA320.
Siginificant temperature measurement accuracy
improvement can be obtained using a temperature
sensor that is matched to a transmitter. This matching
process entails teaching the transmitter the relationship
between resistance and temperature for a specific RTD
sensor. This relationship, approximated by the
Callender-van Dusen equation, is described as follow-
ing :
R t = R 0 {1 +
α
(1+0.01
δ
) t -
αδ
/ 10 4 t 2 -
αβ
/ 10 8
(t -100 ) t 3 }
where : Rt = Resistance (ohms) at
Tempearature t ( o C)
R 0 = Sensor -specific constant
(Resistance at t=0 o C)
α
(alpha) = Sensor-specific constant
δ
(delta) = Sensor-specific constant
β
(beta) = Sensor-specific constant
(0 at t>0 o C)
Although the sensor curve is standardized, the exact
values for R
0 ,
α
,
δ
and
β
are specific to each RTD
sensor and are obtained by testing each individual
sensor at various temperatures. These constants are
known as Callender-van Dusen constants.
Generally, the constants R 0 , A, B, and C are also used
as the characteristic coefficients of the RTD instead of
R
0 ,
α
,
δ
and
β.
These are derived from IEC Standard
Curve and the relationship is described as followings ;
R t = R 0 {1 + At - Bt 2 + C (t -100) t 3 }
where : Rt = Resistance (ohms) at
Tempearature t ( o C)
R 0 = Sensor-specific constant
(Resistance at t=0 o C)
A = Sensor-specific constant
B = Sensor-specific constant
C =Sensor-specific constant
(0 at t > 0
o C)
These two equations are equivalent. A model YTA
can cope with either case as above-mentioned.