<2. Connecting the BT200>
2-1
IM 01C50T03-02EN
2. Connecting the BT200
2.1 Interconnection Between
YTA and BT200
IMPORTANT
• Analog output may change temporally in
connecting with BRAIN terminal due to
an initial current flowed to it. To prevent
communication signal affecting the upper
system, it is recommended to install a
lowpass filter (approximately 0.1s).
• Communication signal is superimposed on
analog output signal. It is recommended to
set a low-pass filter (approximately 0.1s) to
the receiver in order to reduce the output
effect from communication signal.
Before online-communication, confirm that
communication signal does not give effect on
the upper system.
WARNING
Do not attempt to use the BT200 in a dangerous
environment where explosive gas or inflammable
vapor is generated.
The BRAIN communication signal is superimposed
onto the 4 to 20 mA DC analog signal. Since
the modulated wave is a communication signal,
superimposing it on the normal signal will,
from basic principles, cause no error in the DC
component of the analog signal. Thus, monitoring
can be performed via the BT200 while the
transmitter is on-line.
As shown in Figure 2.1, there are two methods of
connecting the transmitter and the BT200: the first
is to use the BT200 connection hook provided in the
terminal box and the other is to use a terminal board
or relay terminals on the transmission line.
YTA
BT200
BT200
BT200
F0201.ai
BT200
Relay
terminals
4 to 20 mA DC
signal
transmission
line
Control room
Terminal
board
Distributor
Figure 2.1
Connecting the BT200
2.2 Communication Line
Requirements
[Protocol specification] Yokogawa original protocol
[Modulation] Burst modulation
0: 2400Hz
1: Signal without carrier
[Baud rate] 1200bps
[Communication signal]
host to device: +/- 0.5V (load resistance 250Ω)
device to host: +/- 2mA
F0202.ai
YTA
BT200
cc
Cable
resistance Rc
Cable resistance Rc
Load
resistance R
Power
supply
● Loop resistance = R + 2Rc
= 250 to 600 Ω
● Loop capacitance = 0.22 µF max.
Figure 2.2
Communication Line Requirements
