Overview
Isolated (supposedly optically) RS-232 to RS-485 converter, useful for controlling VFD's over half-duplex Modbus, though the converter supports full duplex.
Wiring Diagram
RS-232
Female DE9 RS-232 pinout:
| DE9 Pin
|
Function
|
Direction
|
Note
|
| 1
|
PGND
|
PC ↔ device
|
normally DCD
|
| 2
|
RXD
|
PC ← device
|
|
| 3
|
TXD
|
PC → device
|
|
| 4
|
DTR
|
PC → device
|
|
| 5
|
GND
|
PC ↔ device
|
|
| 6
|
DSR
|
PC ← device
|
|
| 7
|
RTS
|
PC → device
|
|
| 8
|
CTS
|
PC ← device
|
|
| 9
|
RI
|
PC ← device
|
|
RS-485
RS-485 screw terminal header:
| Pin
|
Name
|
RS-422 Function
|
RS-485 Function
|
| 1
|
T/R+
|
TX A+
|
RS-485 (A+)
|
| 2
|
T/R-
|
TX B-
|
RS-485 (B-)
|
| 3
|
RXD+
|
RX A+
|
|
| 4
|
RXD-
|
RX B-
|
|
| 5
|
SGND
|
GND
|
| 6
|
Bill of Materials
| Name
|
Package
|
Marking
|
Description
|
Link
|
| U1,U4
|
SOIC-8
|
SP3485E; 1749L; T17210
|
half-duplex RS-485 transceiver
|
MaxLinear SP3485EN-L
|
| U3
|
SOT-23-5
|
L00A
|
3.3V ultra low dropout voltage regulator
|
Texas Instruments LP2980AIM5-3.3
|
| U5,U6
|
SOIC-14
|
NXP HEF4093BT; CSA59001; TXD17383
|
quad 2-input NAND Schmitt trigger
|
NXP HEF4093BT,652
|
| U7
|
SOIC-8
|
[Top Power ASIC logo] TP7660; 1749H
|
voltage converter
|
Chinese datasheet
|
| R1,R3,R7
|
0603
|
472
|
|
|
| R4,R8,R9
|
0603
|
472
|
|
|
| R5,R6
|
0603
|
122
|
|
|
| C3
|
|
226C; 83EH0
|
|
|
| C2,C5,C6
|
|
106C; 20EH4
|
|
|
| C1,C4,C7,C10,C11,C12
|
0603
|
|
|
|
| C8, C9
|
"B" size
|
106C; 10FN0
|
|
| Q2,Q3,Q4,Q6
|
SOT-23
|
C3
|
|
|
| Q1,Q5
|
SOT-23
|
M6
|
|
|
| D1,D2
|
?
|
M4
|
|
|
| ZD1,ZD22,ZD4,ZD5
|
|
[B logo] C803; AK
|
|
|
| ZD3
|
|
SS24
|
|
|
| JP1
|
|
ZHONGB; ZB126; 300V 10A; CE 20-14 AWG
|
(Ningbo Zhongbo Photovoltaic Technology Co., LTD) 6-position 5.0mm pitch screw terminal block
|
datasheet datasheet (alt)
|
| JP2
|
|
|
female DE-9 solder cup connector (PCB mounted though!)
|
|
| JP3
|
|
GongKin DC-002-⌀1.0
|
small (4.2mm OD, 1.0mm ID) DC barrel jack mating with a 3.5x1.35mm plug
|
深圳市冈琦电子有限公司
|
| T1
|
|
UTEK 05S05S-W1
|
|
|
Online Resources
RS-232 to RS-485/422 Port-Powered Lightning Converter with Optical Isolation
User Manual
