IKA RET control-visc - Manual (Page 30)

30
Power supply
connection
PT 100 / PT 1000 plug
RS 232
BNC connector (only for pH probe)
Pt1000-2
5
3 1
4
2 Pt1000-1
Pt100 5
3 1
4
2
9-pin connector
Serial RS 232 interface and USB
Configuration
The RS 232 serial interface can be used to operate the device
using a computer and a suitable user program (labworldsoft).
In order to increase safety when operating the RET using a
PC, a watchdog function can be activated which monitors
the continuous data flow (see section entitled: “Watchdog
function”).
• The functions of the interface circuit between the laboratory
device and the automation system are a selection from the
signals specified in the EIA standard RS232 as per DIN 66020
Part 1. The assignment of the different signals can be seen in
the image.
• Standard RS 232, corresponding to DIN 66259 Part 1 is valid
for the electronic characteristics of the interface circuits and
assignment of signal states.
• Transmission process: asynchronous character transmission in
start-stop operation.
• Transmission type: full duplex
• Character format: character composition according to data
format in DIN 66022 for start-stop operation. 1 start bit,
7 character bits, 1 parity bit (even), 1 stop bit.
• Transmission speed: 9,600 bit/s
• Data flow control: hardware handshake RTS/CTS
RTS: (PIN 7) LOW (positive voltage)
/ COMPUTER can transmit
RTS: (PIN 7) HIGH (negative voltage)
/ COMPUTER cannot transmit
CTS: (PIN 8) LOW (positive voltage)
/ COMPUTER ready-to-receive
CTS: (PIN 8) HIGH (negative voltage)
/ COMPUTER not ready-to-receive
• Access method: data transmission from the device to the
computer only occurs after a request from the computer.
Command syntax
The following points should be noted for the instruction set:
• Commands are generally sent from the computer (master) to
the lab device (slave).
• The lab device only responds to requests from the computer.
• Commands and parameters, as well as consecutive parameters,
must be separated by at least o n e space (code: hex 0x20).
• Each individual command including parameters and data and
all responses are completed with CR LF (code: hex 0x0D and
0x0A) and can have a maximum length of 10 characters.
• The dot is used for decimal separators in a floating-point value
(code: hex 0x2E).
The details given above generally comply with the recommendations
of NAMUR (NAMUR recommendations for the design of electrical
plug-in connectors for analogue and digital signals in laboratory
MSR devices. Rev. 1.1).
Summary of available NAMUR commands
Abbreviations used:
X,y = numbering parameter (integer)
m = variable value, integer
n = variable value, floating-point number
X = 1 medium temperature(external temperature sensor)
X = 2 hot plate temperature
X = 3 hot plate safety temperature
X = 4 speed
X = 5 viscosity trend
X = 7 heat transfer medium temperature
X = 80 pH value
X = 90 Weight value
X = 54 Error 5 response time in seconds (180 <= n <= 1200)
X = 55 Intermittent mode cycle time in seconds
( 10 <= n <= 600 )
X = 56 Intermittent mode, duration of interruption in seconds
( 5 <= n <= 60 )