U90 Ladder 6.1.0a Bugs Fixed	Fixed in the current version
Telit modem: fixes certain timeout errors
CANbus ISC: defining SI (3,200) sometimes caused error

U90 Ladder 5.2.4 Bugs Fixed	Fixed in the current version
Statistics showed 8 keypad entry limits, while in fact there were 16..

U90 Ladder 5.07 Bugs Fixed	Document version: 03/09/06
Time based security component mistakenly caused the application to stop working 45 days after installation-fixed.
Downloading an O/S in systems where the numbering schema uses a comma (,) to denote fractions caused an RTE.

U90 Ladder 5.07 Bugs Fixed	Document version: 03/09/06
Time based security component mistakenly caused the application to stop working 45 days after installation-fixed.
Downloading an O/S in systems where the numbering schema uses a comma (,) to denote fractions caused an RTE.
U90 Ladder 5.02
Bug: Software Version	Bug report	What to do
V5.00 to V5.02	Incorrect HSO descriptions Previous to V5.00, in Hardware Configuration, under High-Speed-Output (HSO), HSO was listed in this order: Frequency PWM In V5.00, 5.01, and 5.02, HSO was listed in this order: PWM Frequency In the PLC, the first operand is always used for Frequency, and the second one for PWM, regardless of the operand description. Note that the incorrect descriptions do not influence the program.	This has been fixed in V.503. If you created projects using HSO in versions 5.00, 5.01, and 5.02, open them in V5.03 and update the HSO operand descriptions, so that they are listed in this order: Frequency PWM
U90 Ladder 5.0
Known Issue M90/91/Jazz OS 3.72 Build 01 This issue is specific to controllers with 2-line displays and multi-language support. In these controllers, OS 3.72 B01 may have caused the cursor on the controller's LCD screen to be incorrectly positioned. Fix Use OS 3.72 Build 02 and higher. You can use U90's Live Update feature to download a new OS from the Unitronics web site. Check the Help topic Live Update from the web to learn how to download an OS and install it into the controller.
U90 Ladder 4.01
Fixed in V4.01 Early versions of U90 Ladder did not support PID loops. When old projects created with these versions were opened with later versions supporting PID loops, and then downloaded, a run time error may have resulted.
M90/91 OS
Bug: OS Version	Bug report	What to do
O/S 3.70, Builds 00 & 01	In some cases, U90Ladder nets containing transitional rise or fall elements did not process the net logic as expected.	Install O/S 3.70, Build 02 and higher.
U90Ladder
Bug: Software Version	Bug report	What to do
v1.00 to v3.81	If an U90Ladder project containing an HMI variable linked to MI 121 was uploaded, the uploaded variable was changed to Date format.	Use U90Ladder versions 3.81 and higher.