I have some problems running a PID-Temperature Controller. It works
fine most of the time, but tends to crash with varying frequency
(months to hours).
So yesterday, I changed from the old python module to the ownet
interface (but still use the old v2.4.1 owserver binary) and
encountered the following error (obviously during the read of a
temperature sensor)
ValueError: negative buffersize in recv
The program is very simple: It reads the temperature every minute,
calculates the updated P, and I gains and the correction terms from
those. If the term is 0 or 1, the heater is turned off or on, if it
is inbetween, the heater is put into PWM mode. Most of the writing I
encapsulated in "try." already, but since yesterday I know that the
problem seems to be (also?)the temperature reading.
Any suggestions? Since the first implementation of this regulator, I
rewired the bus using CAT5 cables, and I removed all the "star"-parts
from the topology. Cable length is less than 50m, the connection is
done via a MOXA port server, a serial-to-1wire converter including a
filter.
The circuits we use are available at
http://www.aip.de/People/wbittner/1wire/index.html
Sorry, only in German:
"Spannungseinspeisung am Master Kabel auch hier!" is the serial-ow
converter
"Temperatursensor für Daisy Chain Verkabelung mit RJ12 Anschluß für
Sensoren" is the Temperature sensor
"PWM Modul für Heizungsregelung" is the PWM-heater module
Dr. Michael Weber
Astrophysikalisches Institut Potsdam
An der Sternwarte 16
D-14482 Potsdam
Tel: 0331 7499 351
Fax: 0331 7499 200
email: [EMAIL PROTECTED]
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