Omron integer subtract error

Hello,

Something wrong with BCD and integer conversion it seems. I want to subtract 1 every second from a register, but something strange is happening , starting value in register is 1300 , now on every rising edge of 1 sec pulse i am subtracting 1 from it, result is ok till it reaches 1280 and then results are abrupt, it jumps to 1270, 1255, 1201 etc. Same thing happens for other register values. Instead of subtract instruction i used decrement still problem is same. I converted integer value coming into this register from hmi into BCD and back but problem remains.
Pls help , thanks

If your number jumps abruptly from 1300 to 1277 then you operation is counting in Octal.
while you are expecting it to display as decimal, or BCD.

I think I will go with a change of mind here,I now think its counting in decimal and displaying in Octal, hence the jump.
Play with the windows Scientific calculator entering 704 then 703 decimal and your answer will be 1300 then 1277 octal

What model PLC are you using, can you post your code?

What model HMI are you using?

Thanks ,

Problem solved , it was indeed octal.