User Manual Part 1

CHAPTER 5
RS-232C/422/485 INTERFACING
Revised: 8 Oct 03 5-4 EST P/N AA104
RS-422/485 CONFIGURATION
The ESTeem will support the requirements of the EIA Standard RS-422/485. This is a four (4) wire interface consisting of the
TRANSMIT DATA (-), TRANSMIT DATA (+), RECEIVE DATA (-), AND RECEIVE DATA (+) or a two (2) wire interface using
B (+) and A (-). These signals are available at the 25 pin RS-232C connector on the modem.
Pin Description
9 BTR (-) TRANSMIT DATA (-)
10 BTR (+) TRANSMIT DATA (+)
14 BRX (+) RECEIVE DATA (+)
DCE
(4-Wire)
16 BRX (+) RECEIVE DATA (-)
14 (+) HALF-DUPLEX B (+)
DCE
(2-Wire)
16 (-) HALF-DUPLEX A (-)
This interface is designed to provide unipolar differential drive to twisted pair or parallel wire transmission lines.
Note: The ESTeem is configured at the factory for RS-422 interfacing. RS-485 (either 4 or 2 wire mode) requires internal
jumper configuration. Please contact EST Customer Support at 509-735-9092 for instruction.
The ESTeem can be factory configured RS-485 interfacing prior to shipment. Call EST Customer Support on 509-
735-9092 for further details.
RS-232C/422/485 Configuration Tables
On the front plate of the ESTeem is a two position RS-232 Setup switch
labeled SW. The switch positions are defined as follows:
RS-232C/422/485
SETUP SWITCH TABLE
BIT 1 OFF Default baud rate 19.2K, N, 8, 1
BIT 1 ON Use software to select baud rate
BIT 2 OFF Enter Command Mode upon
initialization
BIT 2 ON Enter Conversation Mode upon
initialization
Note: *The ESTeem is configured at the factory for RS-422 interfacing.
RS-485 (2 or 4 wire) requires internal jumper configuration. Please
contact EST Customer Support at 509-735-9092 for instruction
ESTeem RS-232C/422/485
Port Pin-Out Table
Pin No. Function
1 Shield Ground
2 Transmit Data (TxD)
3 Receive Data (RxD)
4 Request To Send (RTS Input)
5 Clear To Send (CTS)
6 Data Set Ready (DSR)
7 Signal Ground
8 Data Carrier Detect (DCD)
19 Mode Control
20 Data Terminal Ready (DTR)
22 Ring Indicator (RI)
12 Request To Send (RTS Output)
9* RS-422/485 Transmit Data (-)
10* RS-422/485 Transmit Data (+)
14* RS-422/485 Receive Data (+)
16* RS-422/485 Receive Data (-)