092008
14.1.2
Instruction syntax
Here applies the following:
• The instructions are generally sent from the processor (master)
to the laboratory instrument (slave).
• The laboratory instrument exclusively sends on demand of the
processor. Even error codes cannot be spontaneously commu-
nicated from the laboratory instrument to the processor (auto-
matic system).
• The instructions are transmitted in capital letters.
• Instructions and parameters as well as subsequent parameters
are separated by at least o n e blank (Code: hex 0x20).
• Each individual instruction including parameters and data as well
as each reply are terminated with CR LF (Code: hex 0x0D and
0x0A) and have a maximum lenght of 80 characters.
• The decimal separator in a floating point number is the point
(Code: hex 0x2E).
The above statements largely correspond with the recommenda-
tions of the NAMUR-Association. (NAMUR-recommendations for
the design of electric plug connections for the analog and digital
signal transmission to laboratory - MSR individual units. Rev. 1.1).
14.1.3
Overview of the NAMUR-instructions
Abbreviations:
X,y =
Numbering parameter (integer number)
m =
Variable value, integer
n
=
Value of variable, floating point number
X
= 1
PT 100 or PT 1000 medium temperature
X
= 2
Heating plate temperature
X
= 3
Heating plate - safety temperature
X
= 4 Speed
X
= 5
Viscosity trend
X
= 7
PT 1000 heat transfer medium temperature
14.1
Serial RS 232 C interface
14.1.1
Configuration
The unit can be controlled from an external PC (using the dedica-
ted software labworldsoft) via the RS 232 C serial interface fitted
to the unit.
To increase safety when controlling the RET control-visc/C
from a PC, enable the watchdog function for monitoring the
continuous serial data flow (see section 14.1.4).
• The functions of the interface lines between laboratory instru-
ment and automation system are selected from the specified
signals of the EIA-standard RS 232 C, corresponding with DIN 66
020 Part 1. The allotment of the bushing can be taken from illu-
stration.
• For the electrical properties of the interface lines and for the
allotment of the signal status, standard RS 232 C, corresponding
with DIN 66 259 Part 1 applies.
• Transmission method: Asynchronous signal transmission in start
-stop-operation.
• Mode of transmission: Fully Duplex.
• Character format: Character imaging acc. to data format DIN 66
022 for start-stop-operation. 1 start bit; 7 character bits; 1 parity
bit [straight (even]); 1 stop bit.
• Transmission speed: 9600 bit/s
• Data flow control:
Hardware handshake RTS/CTS
RTS: (pin 7) LOW (positive tension)
/ computer may send
RTS: (pin 7) HIGH (negative tension)
/ computer may not send
CTS: (pin 8) LOW (positive tension)
/ computer recipient
CTS: (pin 8) HIGH (negative tension)
/ computer not recipient
• Access method: Data communication from laboratory instru-
ment to computer is only possible on demand of the computer.
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