Reading binary magnetic field with Matlab - matlab

Question

I am trying to read some magnetic fields using Matlab. To do so, I am using Windows XP OS and I am sending the command to continuos reading from the device using Putty. While Putty its running and saving the log file I am reading this log file on Matlab. The Device is a HMR2300.
When I am reading this using ASCII format I am not facing any problems at all. However, I need to collect this data in binary and this is the problem.
The output string is 7 bytes long "Xh|Xl|Yh|Yl|Zh|Zl|" Xh = Signed Byte, X axis - Xl= Low byte, X axis.
Since I have four devices, I am collecting all data inside of a while loop with this code:
%*****% Reading from Device 01
[D1, N] = fread(FidMag1, 7);
while (true)
MagData1 = [MagData1, D1'];
CRLF1 = find(MagData1 == 13);
CRLF1 = [0, CRLF1]';
if (CRLF1(end) ~= 7)
MagData1(1:CRLF1(end))=[];
[D1, N] = fread(FidMag1, 7);
else
break;
end
end
ttt = clock();
TimeStamp1(Count) = ttt(6) + ttt(5)*60 + ttt(4)*3600;
NoCalMagX1(Count) = int16(typecast(uint8(MagData1(1)), 'int8')) * int16(256) + (MagData1(2));
NoCalMagY1(Count) = int16(typecast(uint8(MagData1(3)), 'int8')) * int16(256) + (MagData1(4));
NoCalMagZ1(Count) = int16(typecast(uint8(MagData1(5)), 'int8')) * int16(256) + (MagData1(6));
MagData1(1:CRLF1(end))=[];
So, after that I am reading in a row devices 2, 3, and 4.
This is my result:
Image Link
You can see roughly that before and after 200 sec I am having a delay to collect the data and this is what I need to solve. Usually when my field starts to change, I start to receive a delay and I don't know how to solve it.
I've tried to do a different approach with my code however this is just worst then the first one:
%*****% Reading from Device 01
if (SYNC_1)
[D1, countB] = fread(FidMag1, 7-BIB_1);
if (countB ~= 7)
for a=1:countB
temp(BIB_1+a) = D1(a);
end
end
if (flag_temp)
flag_temp = 0;
else if(find(D1 == 13) == 7)
for a=1:countB
temp(a) = D1(a);
end
end
end
BIB_1 = BIB_1 + countB;
if(BIB_1 == 7)
if (find(temp == 13) == 7)
ttt = clock();
TimeStamp1(Count_1) = ttt(6) + ttt(5)*60 + ttt(4)*3600;
NoCalMagX1(Count_1) = int16(typecast(uint8(temp(1)), 'int8')) * int16(256) + (temp(2));
NoCalMagY1(Count_1) = int16(typecast(uint8(temp(3)), 'int8')) * int16(256) + (temp(4));
NoCalMagZ1(Count_1) = int16(typecast(uint8(temp(5)), 'int8')) * int16(256) + (temp(6));
fprintf('SENSOR B\nX:%.0f Y:%.0f Z:%.0f\n\n', NoCalMagX1(Count_1), NoCalMagY1(Count_1), NoCalMagZ1(Count_1));
Count_1 = Count_1 + 1;
else
SYNC_1 = 0;
end
BIB_1 = 0;
end
end
if (~SYNC_1)
[D1, countB] = fread(FidMag1, 7-BIB_1);
BIB_1 = BIB_1 + countB;
if (BIB_1 > 0)
index = find (D1 == 13);
if(index)
BIB_1 = 7 - index(end);
if(BIB_1 == 0)
flag_temp = 1;
for a=(BIB_1+1):7
temp(a-BIB_1) = D1(a);
end
else
for a=(index+1):countB
temp(aux) = D1(a);
aux = aux + 1;
end
end
aux = 1; %temp index
SYNC_1 = 1;
else
SYNC_1 = 0;
BIB_1 = 0;
end
end
end
Results:
Image Link
Do you guys have any idea how can I solve this? To collect data using ascii my approach its similar and I don't have any problems. Also when I am reading from just one device using the first code I don't have any problems too. I am just lost in how to solve that.