Comet system forum
Discussion forum about Comet system products
Temperature, Humdity,
Pressure Transmitters
and Data Loggers
You are not logged in.
#1 08-04-2008 16:07:22
- zenzo
- Member
- Registered: 08-04-2008
- Posts: 4
T3118 - reading problem
Hi there.
I read from two analogic sensors T3118 and onother device, four loop current signals: T°C and %RH.
The signals are sent to a moxa 2240 from the field trough the two unitilized couples of an ethernet cable.
The reading of T3118 are the same in both channel (I1 and I2) and seem to be the %RH value. The LCD, however, displays reasonable values for temperature and %RH. What are going on?
I would try to check the setting via software trhough an usb cable, how I have to make the USB cable wiring?
Tanks in advance.
Offline
#2 09-04-2008 08:00:35
- PetrS
- Administrator
- Registered: 29-05-2007
- Posts: 34
Re: T3118 - reading problem
See device manual page 6, part Info mode. There is a description how to check sensor's output setting.
Cable for transmitter adjustment via USB port includes some HW, it is not only wire. It is an optionally accessory, you can buy it. Its part number is SP003.
I don’t understand well your connection through Ethernet cable, is the same cable (other pairs) used simultaneously for Ethernet communication too? If so, it is not much good, it can provide undesirable induction of interference signals.
Offline
#3 09-04-2008 10:54:36
- zenzo
- Member
- Registered: 08-04-2008
- Posts: 4
Re: T3118 - reading problem
Yes, I'm using the same cable (others pairs) used simultaneously for ethernet comunication betwen an digital output MOXA and analogical input MOXA. In the experimental setup the ethernet cables are very shorty, anyway I've wired directly the T3118 with the MOXA and the reading is:
I1=11.26 mA (%RH)
I2=11,39 mA (T°C)
the display shows I2=23.2°C and I1=45.8 %RH. The loop current range is 4-20mA and the sensore range (from info mode) is 0-100%RH for I1 and 0-50°C for I2, so the currents I read are wrong.
Any suggestions?
P.S.
I'll try to get the SP003 item if you think that it can be usefull to resolve the issue of reading.
Offline
#4 09-04-2008 12:19:58
- zenzo
- Member
- Registered: 08-04-2008
- Posts: 4
Re: T3118 - reading problem
I'm so sorry ...
It was a my mistake. I was applying the wrong equation to convert the corrent neasured in °C or %RH!!!
With the right eq, now, the values shown from the display are equal to the values that are calculated from the right equation.
Tanks a lot.
Offline
#5 09-04-2008 12:57:02
- PetrS
- Administrator
- Registered: 29-05-2007
- Posts: 34
Re: T3118 - reading problem
I don’t understand you well, what is wrong?
I1=11,26mA, I1=relative humidity, range 0 to 100% RH, analog output 4 to 20mA, it means (100/(20-4))*(11,26-4) = 45,4% RH display shows 45,8%, difference is probably done by humidity change during current measurement and display reading
I2=11,39mA, I2=temperature, range 0 to 50°C, analog output 4 to 20mA, it means
(50/(20-4))*(11,39-4) =23,1°C, display shows 23,2°C
Offline
#6 09-04-2008 13:02:38
- PetrS
- Administrator
- Registered: 29-05-2007
- Posts: 34
Re: T3118 - reading problem
Ok, that is fine.
I can recommend to you our program Conversions.exe, it is free to download at
http://www.cometsystem.cz/english/downl … lities.htm
use tab Current loop.
Offline
#7 09-04-2008 13:12:26
- zenzo
- Member
- Registered: 08-04-2008
- Posts: 4
Re: T3118 - reading problem
Tankyou P. for the suggestions.
Bye.
Offline