Assuming this is the data sheet
http://www.i2c.byvac.com/downloads/B...0DataSheet.pdf

On the other hand, if I use assembler and write the communication from LAB-X1 to ByVac I2C interface to LCD in assembler, I can use without problems all ByVac interface's commands ... $03, $20, $25... etc., while PBP has problems.
From what I see on the above data sheet that would be correct. The display is not setup to have more than one on a bus so it does not use a control bit.

Looks like you will have to use SHIFTOUT. But if you have an ASM routine working just put that into the PBP code.