Texas Instruments RS-485 Half-Duplex Evaluation Module RS485-HF-DPLX-EVM RS485-HF-DPLX-EVM Datenbogen
Produktcode
RS485-HF-DPLX-EVM
3.3V
PSU1
R
JMP3
1
2
2
VCC
3
4
JMP2
1
2
2
VCC
3
4
/RE
DE
JMP6
1
2
2
3
4
B
A
1
JMP11
2
3
3
1
2
3
TB1
G
N
D
E
A
R
T
H
V
C
C
1
2
3
TB2
Scope
Ch4
Ch3
Ch2
Ch1
B
A
PSU2
Signal
Generator
JMP4
1
2
VCC
3
4
D
JMP3
1
2
VCC
3
4
JMP2
1
2
VCC
3
4
/RE
DE
1
JMP14
2
3
1
2
3
TB1
G
N
D
E
A
R
T
H
V
C
C
1
2
3
TB2
B
A
3.3V
3.3V
PSU1
V
CM
PSU2
Scope
Ch4
Ch3
Ch2
Ch1
3.3V
Signal
Generator
JMP4
1
2
2
VCC
3
4
R
D
JMP3
1
2
2
VCC
3
4
JMP2
1
2
2
VCC
3
4
/RE
DE
JMP6
1
2
3
4
1
JMP11
2
3
3
1
JMP14
2
3
3
1
2
3
TB1
G
N
D
E
A
R
T
H
V
C
C
JMP7
1
2
3
4
R9
375W
R8
375W
3.3V
Powering Up the EVM and Taking Measurements
•
replace R5 (120-
Ω
default) with 60
Ω
•
replace R8 and R9 (0-
Ω
default) with 375
Ω
•
connect pin 2 of JMP7 with pin 1 and pin 3 with pin 4
•
replace the previous wire-bridge at TB1 with a second power supply unit (PSU2) and connect the
ground terminals of both, PSU1 and PSU2 with a wire-bridge, as shown in
ground terminals of both, PSU1 and PSU2 with a wire-bridge, as shown in
Figure 8. RS-485 Half-Duplex EVM Setup for Maximum Loading
Note that
only shows the wiring of PSU2 for positive common-mode voltages. For negative
V
CM
, connect the ground terminal of PSU2 with pin 1 of TB1 (EARTH), and the V
CM
-output of PSU2
with the ground terminal of PSU1.
Figure 9. RS-485 Half-Duplex EVM Configurations: Left as Receiver EVM, Right as Transmitter EVM
7
SLLU173B – October 2012 – Revised June 2013
RS-485 Half-Duplex Evaluation Module
Copyright © 2012–2013, Texas Instruments Incorporated