K8047 data logger/recorder erratic data recording

Kits PC Related Projects
1

Dear forum members,

I am using K8047 data logger/recorder for recording dc voltage from different solar panels. For testing the performance and correct functioning of the k8047 logger I have connected a constant voltage variable DC power supply to one of the channel of the data logger .I have set the full scale input voltage of 30V and the corresponding gain of 1 in the source code developed in VB with a Time scale setting of 100S=1 second i.e., to acquire 1 data for every 10ms.

The program I have developed is working fine and I could able to record 100 data for one second and 6000 data for one minute.

But the problem I am now facing is something unusual .Though I have linearly increased the input voltage to the logger in a step 50 mv(millivolt) increment i.e ., I started increasing the input voltage to the logger in a step of 4.00 V 4.05 ,4.10,4.15,4.20,4.25 V,4.30,4.35 V ……………(I observed the input voltage to logger in a high precision Agilent 34401a digital multimeter)
The corresponding voltage recoded in the k8047 logger/recorder not varying linearly according to the variation in the input voltage. I observed that it is varying at a step of 120 mv 1.e ., 4.00v, 4.120V,4.280V ,4.400V,4.520V,4.640V, -----------------------.(Please note that the sampling interval is 10ms=1 data and the full scale input voltage selected is 30V).

When the program reads the timer counter status and the data from the A/D of K8047 logger/recorder to a buffer in the application program for every 10ms i.e increment of timer counter for every 10ms the new data from the A/D converter channels must be updated every time the timer counter is incremented. But the data is not getting is not getting updated and increasing in a step of 120 millivolt.

I am also getting the same stepped increment of voltage for all the four channels. I think the problem must be either in my source code or in the k8047 logger/recorder which I presume is remote.

Also there is a drop in the voltage recorded and I am not bothered now .But I am very much bothered about the erratic recording the data in a step of 120 mv.

As I am very much depending on the k8047 recorder/logger for my project the technical problem I am facing now is bothering me much. I request the forum member to clarify my doubt and offer me a solution please.

Cordially yours

kuma252982
Kuma252982

2

[quote]I request the forum member to clarify my doubt and offer me a solution please.[/quote]I’m sorry there is no solution.
The analog to digital converter of the K8047 is 8 bit.
The one bit step at 30V full scale is about 120mV.

3

[quote=“kuma252982”][u][color=#000000]Dear forum members,

I am using K8047 data logger/recorder for recording dc voltage from different [/color][color=#000000]solar panels[/color][color=#000000]. For testing the performance and correct functioning of the k8047 logger I have connected a constant voltage variable DC power supply to one of the channel of the data logger .I have set the full scale input voltage of 30V and the corresponding gain of 1 in the source code developed in VB with a Time scale setting of 100S=1 second i.e., to acquire 1 data for every 10ms.

The program I have developed is working fine and I could able to record 100 data for one second and 6000 data for one minute.

But the problem I am now facing is something unusual .Though I have linearly increased the input voltage to the logger in a step 50 mv(millivolt) increment i.e ., I started increasing the input voltage to the logger in a step of 4.00 V 4.05 ,4.10,4.15,4.20,4.25 V,4.30,4.35 V ……………(I observed the input voltage to logger in a high precision Agilent 34401a digital multimeter)
The corresponding voltage recoded in the k8047 logger/recorder not varying linearly according to the variation in the input voltage. I observed that it is varying at a step of 120 mv 1.e ., 4.00v, 4.120V,4.280V ,4.400V,4.520V,4.640V, -----------------------.(Please note that the sampling interval is 10ms=1 data and the full scale input voltage selected is 30V).

When the program reads the timer counter status and the data from the A/D of K8047 logger/recorder to a buffer in the application program for every 10ms i.e increment of timer counter for every 10ms the new data from the A/D converter channels must be updated every time the timer counter is incremented. But the data is not getting is not getting updated and increasing in a step of 120 millivolt.

I am also getting the same stepped increment of voltage for all the four channels. I think the problem must be either in my source code or in the k8047 logger/recorder which I presume is remote.

Also there is a drop in the voltage recorded and I am not bothered now .But I am very much bothered about the erratic recording the data in a step of 120 mv.

As I am very much depending on the k8047 recorder/logger for my project the technical problem I am facing now is bothering me much. I request the forum member to clarify my doubt and offer me a solution please.

Cordially yours
[/color][/u]
kuma252982
Kuma252982[/quote]
Were you able to find the solution? I think it is major issue? Please post suitable reply.

4

The only possible solution is to reduce the input range. As VEL255 said, the data logger uses an 8-bit A/D. At 30V input range one step can only be 30/256=0.1171875 Volts.

Sometimes you don’t need the full range. For example a typical 12V lead-acid battery has a voltage of 10.5V under load at full discharge and is charged at 14.4V. This means that an input range of 0…6V with a level shift of -10V will get you a 2.5 times more accurate measurement than using a 0…15V input range.

Regards,
Jan