[quote user="Duncan"]I am facing a problem while uploading the program from s5 PLC.When I upload the program, after transferring some blocks it gives an error saying "Check sum error" and stops the block transferring from PLC.

Hi friend Duncan,

Normally you can switch on checksum with STEP5, when this is chosen then a checksum behind the blocks is sent to the CPU.

When you load them back with this checkmark on and they are not transfered with the checkmark on then you get a errormessage.

It could also be that a checksum error is realy there, when there is some disturbance it could happen that a checksum error ocur.