iX Talk

I've got a small machine and I am using a T4A to transfer temperature setpoint settings to an Ascon temp controller over Modbus RTU (COM4, RS-485).

I've set up a read/write tag to view/change the setpoint. I use an AnalogNumeric object on the screen. The object works fine. I am able to view the setting in real time and make changes.

I save those settings in a recipe, and everything appears to save properly, as there are no error messages.

The problem occurs when I load recipes. The tag does not update. So, effectively, the load recipe function does not work.

The problem does not occur when using the same technique to change data values in the PLC (Panasonic FP0 using Mewtocol on COM1). They are all part of the same recipe.

Is there something I'm doing wrong? Is there something inherently different about Modbus that causes this?

I've crafted a workaround. I've set the display tag to Read Only, and I use another tag (Write Only) to adjust that variable. Both tags change the same data register in the Ascon controller. I've set the Write Only objects to be invisible unless a supervisor is logged in. The Read Only objects have the Operator Input disabled. Using this method, the recipes load functiion works as expected.

Any ideas? The workaround is okay, but a little kludgey. I'd prefer not to do this.

I'm using iX 2.0.356. The Modbus driver is 5.10.03.

Thanks in advance.

The tag may be updating, but is instantly set back to the original state. Modbus allows you to read/write a tag value. Setting the tag to a value via a recipe does not ensure that the tag will stay at that value. It is similar to manually entering in a number by hand, and should function the same way.

If you unplug the Ascon controller, and then load the recipe, does the tag value change?

The problem occurs even when the comm cable to the Ascon is disconnected. I've also tried it in the Simulate mode on my PC, and the same thing happens.

When I enter the values manually, everything works fine.

I'm currently downloading iX 2.0 SP1, and I will try that as well.

I can send you the program file if you'd like to inspect the code.

I tried it on my PC and it works fine without a controller hooked up. I would create another tag and add it to your recipe for testing and see if that works. You might be altering your tag value somewhere in your project.

Seems a little weird that one of your tags works like you expect, while the other does not. It should not matter what driver you are using. Are you using data exchange on the problem tag?