MT174

ISKRA MT174

ISKRA MT174 (230/400V, rated 85A) mostly used in Saxonia this seems to have some noticable semaphores wich can be visualy inspected:

KD = lid/cover open (there must be a switch somewhere)
BAT = internal battery low
DÜ = transmission mode
FF = "Fatal" counter (?)
SET = counter in program mode

The IR-Interface is claimed to be IEC 62056-21 mode C (asynchron, half-duplex, 300 - 19.200 baud, 7bit, even parity, 1stop (1_7D_1P_E_1S) and it is bidirectional. So one can also send something over that interface. There's an optional RS485 wire interface on some models.

The "Fatal counter" is a hex value 8bit flag register:

0 = Firmware error
1 = Counter parameter checksum error
2 = energy/maximum checksum error
3 = not used
4 = not used
5 = not used
6 = maintenance warning level (?)
7 = not used

Tampering / manipulation log video

Explaining basic concepts