I should also note an observation I’ve had with my code. I’m going from the
Teensy to a Max3232 to the T-102. Even with power off on the 102 I receive
garbage on the port. My code seems to catch all the preambles though to start
a packet. Code is starting to get larger so I’m going to post a Github for
anybody to look at.
Bill
Sent from my iPhone
> On Sep 19, 2019, at 10:17 PM, Bill Nobel <b_no...@hotmail.com> wrote:
>
> Hi John, yes I receive 2 packets fine (with response) then things go strange
> only on checksum. Your C# routine is different from DLPlus for the Calc,
> I’ll try that in the morning and see if that changes.
>
> Sent from my iPhone
>
>> On Sep 19, 2019, at 9:58 PM, John R. Hogerhuis <jho...@pobox.com> wrote:
>>
>> Are you sure you got a full, aligned packet? It starts with ZZ , counted
>> length, no missing characters?
>>
>> The DLPlus checksum is correct. More likely you're misaligned, or somehow
>> dropped, swapped, or corrupted a character.
>>
>> Here is the C# code too for comparison
>>
>> public byte Checksum(byte[] ary, uint ofs, uint fence)
>> {
>> uint sum = 0;
>>
>> for (var i = ofs; i < fence; i++)
>> sum += ary[i];
>>
>> return (byte)((~sum) & 0xff);
>> }
>>
>> Welcome to the cabal of TPDD protocol initiates.
>>
>> -- John.
