11 properties of the rs232 interface, 1 data transfer protocol, 2 handshake – Metrohm 730 Sample Changer Manuel d'utilisation

Page 158

Advertising
background image

4.11 Properties of the RS232 Interface

730 Sample Changer, Detailed Description

155

4.11 Properties of the RS232 Interface

4.11.1 Data Transfer Protocol

The Sample Changer is configured as DTE (Data Terminal
Equipment).

The RS232 interface has the folllowing technical specifications:

Data interface according to the RS232C standard, adjustable
transfer parameters, see pages 86 and 143.

Max. line length:

80 characters + C

R

L

F

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 730 Sample Changer with foreign de-
vices. The cable shield must be properly grounded on both instru-
ments (pay attention to current loops; always ground in a star-
head formation). Only plugs with sufficient shielding may be used
(for example, METROHM K.210.0001 with K.210.9004).

4.11.2 Handshake

Software-Handshake, SWchar

Handshake inputs on the changer (CTS, DSR, DCD) are not
checked.
Handshake outputs (DTR, RTS) are set by the changer.
As soon as an L

F

is recognized the changer sends XOFF. After

this it can still receive and store 6 characters.
The changer also sends XOFF when its input buffer contains 60
characters. After this it can receive 22 extra characters, (including
L

F

).

If the transfer is interrupted for the time of 4 characters after the
changer has sent XOFF, the character string previously received
will be processed even if no L

F

has been sent.

Advertising