Blank LCD

[BC SYSTEMS]

Hi,

I'm trying to get the LCD working on two TMD 2424's, both are using the 4 x 20 LCD.

I have loaded my program that is installed in four other installations but the LCD wont display any characters.

i have loaded a simple section of code that is triggered from Input 1 as follows:

SETLCD 0,1,CHR$(12) ' NO CURSOR
SETLCD 1,1,"KO POT CONTROL V" +STR$(DM[233],2)
SETLCD 2,5,""
SETLCD 3,3,"WWW.BCSYS.CO.UK"    'SETLCD 3,3,"WWW.BCSYS.CO.UK"
SETLCD 4,7,STR$(TIME[1],2)+":"+STR$(TIME[2],2)+":"+STR$(TIME[3],2)

Both PLC's are behaving exactly the same, both PLC and LCD were ordered at the same time.

Have you had any problems with either the LCD or the LCD port?  is there anything I can do to test the LCD or LCD port?

Cheers

[garysdickinson]

Have you checked the LCD contrast adjustment?

It is located near the LCD connector on the PLC board.  

If this is turned fully clockwise, nothing will display on the LCD.

Good luck,

Gary D.

[support]

Usually when the PLC is shipped from the factory the contrast is already adjusted. Try to remove the statement that turn off the cursor. Then at least you know if the LCD is properly initialized if there is a blinking cursor.

If there is a cursor but no other display then the CF that contains SETLCD command may not have been executed.

Also start with a simple program - you can load the "Clock.pc6" program in the samples folder as a test.

[BC SYSTEMS]

Hi,

Thanks for the info.

The contrast is fine, I have been able to get my hands on another LCD which works fine on both PLC's so it looks like the two I have are duff.

Any ideas why the LCD's would fail?  Is there anything I can do to try and bring them back to life?!?

Cheers

[support]

The most common failure to LCD is caused by "hot" plugging or unplugging of LCD into the LCD port when the power to the PLC is not removed. The electronics on the LCD or the PLC is not designed for hot plugging/unplugging.

Another possible failure is to plug the ribbon cable connector onto the LCD in reverse which can also damage the electronics on board the LCD.

Are you using the factory original LCD and factory original cable? Did you check if the cable is working?

[BC SYSTEMS]

Hi,

Yes using the factory cable,  my "spare" LCD works with the leads OK.

Cheers