User's Manual

18
S2510 Reader - Reference Guide April ’00
2.2.1.7 G - RS422/RS485 Communications Interface
Depending on the DIP-Switch configuration, the Reader will communicate via the
RS232, RS422 or RS485 interface. RS422/485 connections are made via the 6-pin
WECO connector (G in Figure 3). Its pin assignment is given in Table 15 and its spec-
ifications are given in Table 16.
Both, the ASCII and TIRIS Bus Protocol can be used with the RS422 interface.
The ASCII protocol (or any other full-duplex protocol) cannot be used with the RS485
interface.
Table 15: RS422/RS485 Connector
Pin Signal Description
Direction
RS422
Direction
RS485
1Rx+/Tx+
RS422/RS485 non-
inverted data
Input Input/Output
2 Rx-/Tx-
RS422/RS485
inverted data
Input Input/Output
3 GND Signal Ground - -
4Tx+
RS422 non-inverted
data
Output/High
Impedance
-
5 Tx- RS422 inverted data
Output/High
Impedance
-
6 GND Signal Ground - -
Table 16: RS422/RS485 Communications Interface - Specifications
Parameter Specification
Mode of Operation Differential
Number of Drivers On Line 32
Number of Receivers On Line 32
Maximum Cable Length 1200 m
Maximum Data Rate 10 Mbits/s
Maximum Common Mode Voltage +12 V / -7 V
Driver Voltage
High > +1.5 V
Low < -1.5 V
Driver Load 60 mA
Driver Output Short Circuit Limit
150mA to GND
250mA to VCC
Receiver Input 12 k
Ω
Receiver Sensitivity ±200 mV
Receiver Hysteresis 60 mV