USB-COM485-PLUS1 FTDI, USB-COM485-PLUS1 Datasheet - Page 12

• Manufacturer Part Number: USB-COM485-PLUS1
• Description: Interface Modules & Development Tools USB to RS485 Convrtr Assembly 1 DB9 Port
• Manufacturer: FTDI

Specifications of USB-COM485-PLUS1

• Interface Type: USB, RS-485
• Data Bus Width: Serial
• Operating Supply Voltage: 5 V
• Product: Interface Modules
• For Use With/related Products: FT232R
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: USB-COM485-PLUS-1

3
3.1
3.1.1 USB
The USB-COM485-Plus1 is a downstream USB 2.0 Device. A standard USB Series “B” receptacle is
reference to USB-F-1001 to facilitate connection to an upstream USB Host or Hub.
Table 3.1 USB "B" Receptacle Pin-Out
3.1.2 RS485
The RS485 port is configured as Data Terminal Equipment (DTE), with a 9-contact D-Sub Pin connector.
Pin assignments are according to TIA/EIA-485. In addition, pin9 of DE-9P may be assigned to provide
+5VDC to an external device with a maximum current draw of 250mA once the USB-COM485-Plus1 has
been enumerated by the system.
Table 3.2 DE-9P RS485 Pin-Out
A 120R Resistor is connected internally between pin 1 and pin 3 of the 9 way D-type connector – see
Figure 2.1
Pin Number
Pin Number
Connections
Shield
External Connectors
1
2
3
4
1
2
3
4
5
6
7
8
9
Input/Output
Input/Output
Input/Output
Case Ground
Bidirectional
Bidirectional
Pin Type
Pin Type
Ground
Ground
Power
Power
N/A
N/A
N/A
N/A
Copyright © 2010 Future Technology Devices International Limited
Description
VBUS = USB Power provided from upstream USB Host or Hub
D– = USB data signal, negative polarity
D+ = USB data signal, positive polarity
GND = USB signal ground
Drain = typically connected to the host PC case
Description
DATA- = Transmit/Receive Data, negative polarity
Pin 2 of 120R Terminating Resistor. Only Required if the USB-COM485-
PLUS1 is the first or last device in a multi-drop RS485 System, to meet
RS485 Termination Requirements.
DATA+ = Transmit/Receive Data, positive polarity
N/A
GND = signal ground
N/A
N/A
N/A
provide +5VDC to an external device
Pin 1 of 120R Terminating Resistor. Only Required if the USB-COM485-
PLUS1 is the first or last device in a multi-drop RS485 System, to meet
RS485 Termination Requirements.
Document Reference No.: FT_000132
USB-COM485-PLUS1 Datasheet
Clearance No.: FTDI# 95
Version 1.21
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