Modbus TCP Retain Issue

PLCnext Engineer
1

Hello ,

I am Using Modbus TCP/IP Library in which i am unable to Retain the Variable.
If i am selecting Retain on Array of Holding Reg. Retain Memory is not sufficient to hold Retain for such a Long Array.
Can you Please suggest how can i Resolve this?

I am using AXC F 1152 with Vijeo Citect SCADA over Modbus TCP/IP
2

The amount of retain memory cannot be increased on an AXC F 1152.

If you don't need [b]all[/b] the data in the array to be retained, then you could create separate variable(s) for the data that really must be retained, and then copy the data from those variables into the Modbus array on every execution cycle.
3

Thanks for Replying.

But the Values which are Coming from MY HMI (Setpoints for Process) will get Zero during Power On/Off Cycle.
As Whole Modbus Array is getting Initialize during first Scan of Power , so what ever Register i am Reading from HMI to PLC are getting Zero during Power On/Off.
4

Is it possible to copy only the items you want to retain from the array at the end of every cycle, and back to the array at the start of every cycle?

Then you only need to make those copy(s) retentive, rather than the complete array.
5

Ok. Thanks I will Check.

I think suggested Logic i can Prepare.
Can You Please suggest Variable for PLC RUN PLC STOP Bit?
It's Not Listed in System variable Group
6

I’m not sure that there is anything suitable. If the PLC is not running, then the PLCnext Engineer application will not be executed and (for example) PLC Status data cannot be evaluated, and Modbus communications will not be possible via the Modbus server in the PLCnext Engineer application.

7

Can i have Modbus TCP Lib Build 9 with 7000 Holding Register Array?

So i can Retain that for my Application Currently available Register are 65536 and such a array i can not Retain due to memory constrain
8

That would require a change to the source code of the library, and unfortunately the source code is not publicly available.

If you really need a custom version of this library, please get in touch with the Phoenix Contact office in your country. They may be able to get the source code for this library, and if so they may agree to build (and support) a custom version of this library for your application.