UTEK UT-2127 RS-232 to RS-485 Converter
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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