CHIYU BF-850 User manual

USB/RS-485/RS-422
BF-850 CONVERTER USER MANUAL
I、FOREWORD
Developing by PC industry, USB interface
replacing many kind of old PC interface step by
step. However, many types of important
equipment still use RS-422/RS-485 interface, in
order to transfer the data between PC and
RS-422/RS-485 interface. That’s why we need
to use USB/RS-422/485 converter.
BF-850 is a converter in common use; it
does not need extra power. It also conforms to
the standard of USB, RS-422 and PR-485, and
be able to transfer USB signal to RS-422 or
RS-485 signal. There has no delay automatic
transfer inside, the unique I/O electric
auto-control the direction of data transfer, and
need no handshake signal (like RTS, ETR) to
transfer with full duplex (RS-422) and half duplex
(RS-485).
BF-850 can provide the reliable connection
between point to point and point to multi-points.
In point to multi-points each converter can
connects 32 units of RS-422 or RS-485 interface
equipment. The speed of data transfer is
300~921600 bps and the communication types
are USB to RS-422, USB to RS-485.
II、Property argument
1. Standard：Conform to the standard of USB
V1.1, EIA RS-485, RS-422.
2. USB signal：VCC、DATA+、DATA-、GND、
FG
3. RS-485 signal：T+、T-、GND
4. RS-422 signal：T+、T-、R+、R-、GND
5. Communication type：Asynchronous
communication, Point to point or point to
multi-points, 2 lines of halt-duplex, 4 lines of
full-duplex.
6. Communication control：use auto-control
technology to transfer the data, automatic
determine and control the direction of data
transfer.
7. Baud Rate：300~921600 bps, automatic
detect the serial port speed.
8. Load ability：In point to multi-points each
converter can connects 32 units of RS-422 or
RS-485 interface equipments.
9. Communication distance：RS-422/RS-485
5000 meter (9600 bps), USB less than 5
meter
10. Type of communication line：Double twist line
or cover line.
11. Communication speed：921600 bps 300 M
38400 bps 2.4 KM
9600 bps 5 KM
12. Dimension：55mm × 36mm × 18mm
13. Operation environment：-25 ~ 70
℃℃,
humidity 5% ~ 95%
14. Support Windows95/98/2000/xp
III、connection and signal
RS-422/RS-485 export signal
DB9
PINS Output RS-422 Duplex
RS-485
Half Duplex
1 T/R+ Transfer(A+) RS-485(A+)
2 T/R- Transfer(B-) RS-485(B-)
3 RXD+ Receive(A+) Empty
4 RXD- Receive(B-) Empty
5 GND Ground Ground
6 N/A
7 N/A
8 N/A
9 N/A
IV、hardware installment and application
Please read the user manual carefully
before install BF-850, connect the USB to PC.
BF-850 use USB/DB-9 connector, and needs no
crossover set to automatic do RS-422 or RS-485
communication type. You can use double twist
line or cover line, so it’s very convenience to
combine it. T/R+ T/R- represent the transfer and
receive A+/B-, RXD+/RXD- represent the
receive A+/B-, GND represent the public ground
line, point to point, point to multi-points
half-duplex connect to 2 lines T/R+, T/R-, point
to point, point to multi-points full-duplex connect
to 4 lines T/R+, T/R-, RXD+, RXD-.
BF-850 provides 4 types of communication
as below：
1. point to point/4 lines full-duplex
2. point to multi-points/4 lines full-duplex
3. point to point/2 lines half-duplex
4. point to multi-points/2 lines full-duplex

When connects to full-duplex or
half-duplex, in order to prevent the
reflection or interference of signal. You
need to connect electric resistance at the
end of line(120Ω1/4W).
V、The connection diagram of communication
USB/RS-422 transfer
1. RS-422 point to point 4 lines full-duplex
communication
2. RS-422 point to multi-points 4 lines
full-duplex
3. between BF-850 full-duplex
USB/RS-485 transfer
1. RS-485 point to point 2 lines half-duplex
2. RS-485 point to multi-points/2 lines
full-duplex
3. between BF-850 half-duplex
VI、breakdown and elimination
1. the failure of data transfer
A. check the USB line connects right or not
B. check RS-422/RS-485 line connects
right or not.
C. Check the terminal connects well or not.
2. data loss or mistake
A. check the transfer speed and format
same or not of both two sides.
T/R+
T/R-
RXD+
RXD-
1
2
3
4
BF-850
R+
R-
T+
T-
RS-422 Equipment
PC1 = >
USB
T/R+
T/R-
RXD+
RXD-
BF-850
R+
R-
T+
T-
RS-422 Eequipment
PC1 = >
USB
R+
R-
T+
T-
R+
R-
T+
T-
1
2
3
4
RS-422 Eequipment
RS-422 Eequipment
PC1 = >
USB
T/R+
T/R-
RXD+
RXD-
1
2
3
4
BF-850
A
< = PC2
USB
RXD+
RXD-
T/R+
T/R-
BF-850
B
3
4
1
2
PC1 = >
USB
T/R+
T/R-
RXD+
RXD-
1
2
4
8
5+
485-
BF-850 RS-485 Ee
q
ui
p
ment
485+
485-
RS-485 Eequipment
1
T/R+
T/R-
RXD+
RXD-
2
BF-850
PC1 = >
USB
485+
485-
4
8
5+
485-
RS-485 Eequipment
RS-485 Eequipment
PC1 = >
USB
A
T/R+
T/R-
RXD+
RXD-
1
2
BF-850
< = PC2
USB
B
T/R+
T/R-
RXD+
RXD-
1
2
BF-850