3 properties of the rs 232 interface, 1 handshake – Metrohm 756 KF Coulometer User Manual

Page 105

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4.3 Properties of the RS 232 Interface

756/831 KF Coulometer, Instructions of Use

97

4.3 Properties of the RS 232 Interface

Data Transfer Protocol

The Coulometer is configured as DTE (Data Terminal Equipment).

The RS 232 interface has the following technical specifications:

Data interface according to the RS 232C standard, adjustable transfer parame-

ters, see page 21.

Max. line length:

512 characters

Control characters:

C

R

(ASCII DEC 13)

L

F

(ASCII DEC 10)

XON (ASCII DEC 17)

XOFF (ASCII DEC 19)

Cable length:

max. approx. 15 m

Start

7 or 8 Data Bit

Parity Bit

1 or 2 Stop Bit

Only a shielded data cable (for example, METROHM D.104.0201) may be used to

couple the Coulometer with foreign devices. The cable shield must be properly

grounded on both instruments (pay attention to current loops; always ground in a

star-head formation). Only plugs with sufficient shielding may be used (for example,

METROHM K.210.0381 with K.210.9045).

4.3.1 Handshake

Software-Handshake, SWchar

Handshake inputs on the Coulometer (CTS) are not checked.

Handshake outputs (DTR, RTS) are set by the Coulometer.

The Coulometer sends XOFF when its input buffer contains 384 characters. After this

it can receive 128 extra characters (including L

F

).

Coulometer as Receiver :

Coulometer

external device

Data output

Data input

max. 128

characters

384 characters

XOFF

XON

L

F

RxD

TxD

Time

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