Wiring
23
4.4.5 Host connection: Modbus Serial, EIA/TIA-232 (RS232)
The NXA822 Data Concentrator is defined as a Data Terminal Equipment (DTE) device, and
provides EIA/TIA-232 (RS232) interface through a male DB9 connector whose pin out complies
with the EIA/TIA-574 standard:
Definition
EIA/TIA-232 (RS232) is a voltage mode digital communication using up to ±12 V
DC
, and requires
a variety of signals depending on the operating mode (software selectable):
RS-232 Cable Specification
Pin RS232 Name Remarks
1 CD Carrier Detect Signal from connected device
2 RxD Receive Data Signal from connected device
3 TxD Transmit Data Signal to connected device
4 DTR Data Terminal Ready Signal to connected device
5 G Signal Ground Common connection
6 DSR Data Set Ready Signal from connected device
7 RTS Request To Send Signal to connected device
8 CTS Clear To Send Signal from connected device
9 RI Ring Indicator Signal from connected device
Case Shield Shield
Signal Basic RS232 Fully RS232 with
Hardware Handshaking
(in preparation)
Remarks
Shield Required Required Copper braided or combined foil and braided
shielding
G Required Required
RxD Required Required
TxD Required Required
RTS Required Null Modem connection, these two pins can be
linked together
CTS Required
DTR Required Null Modem connection, these three pins can be
linked together
DSR Required
CD Required
RI Optional Not required
Cable capacitance ≤ 50 pF/m
Core cross-section ≥ 0.34 mm
2
, corresponds to AWG 22, multi-strand cable is preferred
Cable type Single cable or twisted pair
Cable resistance ≤ 110 Ω/km
Signal damping Max. 9 dB over the entire length of the cable cross-section
Shielding Copper braided shielding or combined foil and braided shielding
To Next Page
Loading...
