Second I2C address not responding

[Archangel]

If you are using NXP data sheet it's hard to understand address, the T I data sheet is more clear the link below to that data sheet
See page 6
http://www.google.com/url?q=http://w...0Ee8TD_UJQnvOw

[LinkMTech]

I'm confused how the 1st I2C address is even responding.

Your device address range, dependent on which address bits are tied HI, is between $40 and $4E according the data sheet.

01000000 = $40 ' With A2, A1, A0 all set to 0 : (bit 0 set to Write) 
01001110 = $4E ' With A2, A1, A0 all set to 1 : (bit 0 set to Write)

Verify which of your PCF8574 address select pins are pulled High and correct them on your current code because other than that it looks right.

Art, the 10ms PAUSE in the manual is referring to writing to an EEPROM that needs that Write delay because it's slow getting out of bed like me.

[Amoque]

The data sheet link passed on by Archangel is much appreciated! Way easier to read... thanks again.

LinkMTech- I have to be honest, the chips may be tha "A" version. I sandwiched the chip between the board and the LCD, so no way to tell, but I also marked each board with a correct address as I verified their function while building. I didn't think to mention the discrepancy because they work individually and it never occurred to me that the addresses could be part of the problem. It does make sense to check this out though as, of course, until the problem is found it may be anywhere.

I am at work presently and have no access to try any of these solutions for some hours, but I will give each every effort and report back soonest.

Amoque

These things are worth the time spent, they are beautiful when lit. Two are very nearly (I mean micro-smidgens different) the same size as the 128X64 GLCDS available in matching background and display color. Already I imagine a modular weather station (like a group of framed pictures) hanging on my den wall with groups of these providing clear visibility from anywhere in the room. Might even throw in a GLCD or two for graph functions. Gold foil touch sensors under glass... I tell ya boys, that's class, and I'm gonna get me some.