Hex string checksum calculation new

[dksingh12]

I have problem in checksum calculation and hoping for help!
I have a hex string with 12 byte in this first byte tells starting point of the data, then 7 bytes are data, byte 9 tell channel countiniously sending data or start/stop, byte 10 tell chanel no. ie. A or B and byte no. 11 & 12 are the checksum values. I'm unable to calculate it. some of the data are as follows
7a:30:30:30:30:36:33:34:31:41:1f:36:
7a:30:30:30:30:36:33:33:33:41:67:1f:
7a:30:30:30:30:36:32:39:33:41:1f:1f:
7a:30:30:30:30:36:32:38:33:41:1f:1f:
7a:30:30:30:30:36:33:30:33:41:3e:1f:
7a:30:30:30:30:36:33:32:33:41:50:1f:
7a:30:30:30:30:36:33:32:33:41:50:1f:
7a:30:30:30:30:36:33:34:33:41:1f:54:
7a:30:30:30:30:36:33:30:33:41:3e:1f:
7a:30:30:30:30:36:33:33:33:41:67:1f:

 

[dksingh12]

Can any one help on it?

 

[_Eduardo_]

First you must help with a useful sample and more info.

Rows 2-10 , 6-7 and 5-9 are the same.


if the last 2 bytes was the checksum, the algorithm might not include 8th byte because row 3-4 has the same "checksum"
(3) 7a: 30:30:30:30:36:32:39: 33:41: 1f:1f:
(4) 7a: 30:30:30:30:36:32:38: 33:41: 1f:1f:

But, if the algorithm not include 8th byte, then rows 2-5-6-7-9-10 should have the same checksum.

Conclusion: The last two bytes does not seem a checksum.

 

[dksingh12]

Thanks for your efforts. I'm including here actual data recieved in Hyper terminal.
Purhaps with that you can help more.

Data starts with (in ascii code) z which denotes that it is starting point.

Then we get 7 bytes of 2500.000mv ( in data dot value not available )

Then byte no. 9 comes with 1 denotes channel started, 2 denotes channel stoped & 3 denotes countineous data coming.

Byte no. 10 have A & B shows Ch1 & Ch2.

Then we get byte no. 11 & 12, which is in my knowledge checksum value

BR

D.K.Singh

 

[_Eduardo_]

If you dump with Hyperterminal, the hex values over 0x80 may change with the character encoding.

--> Dump data with a port sniffer like https://free-serial-port-monitor.software.informer.com/

 

[dksingh12]

Thanks for your reply.

Right now I'm In Austria, Graz. I will be in India in first week of June.

I'll ask to my colleague to take the data as per your suggestion, if he can do this then I will revert back to you. If not then I will contact you in June.

BR

D.K.Singh

 

[dksingh12]

Hallo Eduardo,
Long time ago we were discussing about checksum calculation. I'm still stuked there. As per your suggestion I have taken data from Serial port monitor software, which is more clear data. I'm attaching same. The data contains its loging time, Hex string of actual data and ASCII value of same data.

 

[dksingh12]

Hallo all,

Can any one help on it. on paid basis also.

BR
D.K.Singh

 

[dksingh12]

Hallo all,

Can any one help on it. on paid basis also.

BR
D.K.Singh