Table of Contents
Advertisement
8
Communication via RS-232 and USB-B interface
8.1
General Information
®
The TitroLine
7800 has two serial RS-232-C interfaces to communicate data with other devices. By means of
these two interfaces it is possible to operate several devices on one computer (PC) interface. In addition to that,
®
the TitroLine
7800 also has an alternatively USB-B interface, which can only be used to connect a PC.
RS-232-C-1 establishes the connection to a connected computer or to the previous device of the "Daisy Chain".
At the RS-232-C-2 it is possible to connect additional devices (Daisy Chain Concept).
PIN assignment of the RS-232-C interfaces:
PIN No.
Meaning / Description
1
T x D Data output
2
R x D Data input
3
Digital mass
Chaining multiple devices - "Daisy Chain Concept"
8.2
In order to activate several devices in a chain individually, each device must have an own device address. For
this it is at first necessary to establish a connection from the computer to the RS-232-C interface 1 of the first
devise in the chain by means of a RS-232-C data cable, e.g. Type No. TZ 3097. With the additional RS-232-C
data cable, Type No. TZ 3094, the RS-232-C- interface 2 of the first device is connected with the RS-232-C-
interface 1 of the second device. At interface 2 of the second device it is possible to connect an additional device.
®
The TitroLine
7800 can also be connected via USB cable TZ 3840 (type A (M) - type B (M), 1.8m) to a USB
interface of a PC. To accomplish this connection, a driver has to be installed on the PC. Then the USB-B
interface takes over the function of the RS232-1 interface.
The address always consists of two characters: e.g. address 1 of the two ASCII- characters <0> and <1>.
The addresses can be set from 00 to 15, i.e. 16 possibilities. It must be ensured that the devices in a chain have
different addresses. If a device is addressed with its address, this device will process this command without
sending it to another device. The reply to the computer has also an own address. The addresses are allocated as
described in 6.4 RS-232 Settings.
®
The TitroLine
7800 receives commands from a PC at the interface 1 (USB- B) if the computer knows the
address. It also sends the answer via this interface. If the address of the incoming command does not match the
device address, the complete command will be forwarded to interface 2. Interface 2 is connected to interface 1 of
another device. This device checks the address as well and reacts to the command as the first TitroLine
did before.
All information (data strings) which arrive at interface 2 of the TitroLine
computer via interface 1 (or USB-B interface). Thus, the computer receives the data of all devices. In practice it is
possible to connect up to 16 devices to one computer- (PC-) interface.
8.3
Instruction Set for RS-Communication
The commands consist of three parts:
Adresse, two-digit aa
Command
Variable, if necessary
an end of command
Every command must be completed with the ASCII - sign <CR> and <LF>
Only if the respective action has ended the answers will be returned to the computer.
Example:
The command to dose 12.5 ml shall be sent to the TitroLine
The command consists of the characters:
02DA12.5<CR LF>
in detail:
02
DA
12.5
<CR LF> = Control character as command end
01
e.g.
DA
e.g.
14
e.g.
<CR> <LF>
= Device address
= Dosage command with filling and zero points of the display
= Volume in ml to be dosed
®
7800 will immediately be send to the
®
7800 with the address 2.
(Carriage Return and Line Feed).
281
®
7800
Advertisement
Table of Contents
