User's Manual

29.05.2007 Page 11 of 59
ASR500 Reader Operation
Communication interfaces
To select and activate the required communication interface the jumpers J3, J4 and J5 must be
set as follows:
Figure 3: Jumper settings for RS232
Interface connection RS232
Terminal block ST4 Meaning J3 J4 J5
3 TxD
4 RxD
5 GND
See Figure 3
An RS232 interface needs three wires (TxD, RxD and GND)
TxD: Where a device transmits data
RxD: Where a device receives data
GND: Ground
To use the RS232 interface, connect TxD of the PC to RxD of the ASR500/454, RxD of the PC
to TxD of the ASR500/454 and both Ground signals.
ASR500/454 ST4 Connection PC SUB-D 9 pole
Pin 3 TxD Pin 2 RxD
Pin 4 RxD Pin 3 TxD
Pin 5 GND Pin 5 GND
To detect TxD and RxD disconnect the data lines (TxD and RxD).
Do Voltage measurement between Ground and one of the lines.
The TxD line should be approximately –12V (could be less)
The RxD line should be approximately 0V.
RxD GND
TxD