I have a lot of OP7200 at my customers.
Since a while I see that the backlight of the display is not working anymore.
I have not changed anything in the software.
Is there a known problem with the display or the controller ?
I have the same problem compounded by unreliable contrast settings. On some units it is impossible to increase the contrast to the point where screen is legible. I believe that the latest design changes in the OP7200 have addressed this issue but the older units still remain a serious problem and to date Rabbit has not offered a solution. 
Hi I have the same problem compounded by unreliable contrast settings. On some units it is impossible to increase the contrast to the point where screen is legible.i too want to know about this.
Dissassemble at cursor function was not working in libraries. … and documentation updated for the OP7200 family, which has a new LCD controller. … so when compiling in RAM only mode, some programs may not fit anymore. … OP6800 backlight no longer changes states when toggling the LED’s on the display.
It appears that the LED backlight goes out in less than a year. We have many of these units at factories across the US and all are now virtually unreadable due to the barely visible backlights. Some customers are having to use flashlights to see what is on the display. Note that this is not a contrast problem, it is instead related to the white LED driving the backlighting degrading in its light output very quickly. This needs to be remedied before the OP7200 is a usable product.
For those that may be interested here’s a Blue backlight with white char’s display that will fit into the op7200 and is pin compatible.
You would have to remove the pin header from the original display and install on this one.
For more info google “HD44780-20X4-Character-LCD-Display”
Also a mod to install a 10K pot for adj the display backlight can be installed.
I haven’t checked, but it does seem like the backlight current may need to be limited a little more to prevent premature failure.
I also control the backlight via code so it’s only on when needed i.e. important info (warnings) flashes the backlight and the enter key turns it on for five minutes.
You can code, to suite your needs, certainly better then leaving it on 24/7.
Warning: the Blue display above is not readable without the backlight or I should say it’s very difficult to read w/o the backlight, unlike the green with black char’s.
Thanks but…
The OP7200 does not use a 20x4 display. Are you thinking of some other zWorld terminal?
Well there seems to be some confusion on my part sorry.
The blue / white will work on the OP6700/6600.
I was looking at display options for both displays so it appears that I mixed up the model numbers, sorry.
In any event you can find the OP7200’s display’s on ebay and the code to
control the backlight could still be applied and the 10k pot mod can be used also.
The backlight current should be checked on those displays and adjusted per MFG spec’s.
The 7200 uses a graphics LCD display while the 6700’s use a character LCD.
HTH
A while back we changed our software to only backlight on error and other select points in the operation, which should help. But we are competing with the functionality offered by AB Panelviews, which seem to operate fine without this kind of backlighting degradation.
Could someone from Rabbit please post the expected life of the backlight used in the OP7200 displays ?? This is before we deploy hundreds of these units.