With class 1 TEDS devices like the NI 9233, you connect the EEPROM "backwards" Gnd -> AI+, D+ -> AI-. With class 2 TEDS devices such as the NI 9219 and NI 9237, it is Gnd -> T- and D+ -> T+. This is why you see different results with the serial port based on the connection. This is in section 8 of the 1451.4 specification. The data errors are because the data does not fit.
There are a couple templates that are smaller than 256 bits, but not many and you need to have disabled options. Take a look at some of the TEDS templates. Templates 25 and 27, for example, can be made smaller if you select case 0 for certain options (not specifying functionality).
