Error -1073807254 with cRio 9066 232 port

[Paratore]

System configuration:

I have four PLCs in different locations in communication with a cRio-9066 via two-wire Modbus 485.  The two-wire is daisy-chained into a DTech 485 to 232 converter which is inserted into the integrated 232 port on the cRio 9066 chassis.  I also have a few cDAQ analog output and digital output modules on this chassis.  The device is operating in scan mode using the scan engine.  The programs are developed in LabVIEW 2015 and use the Data Communication VIs for Create Modbus Master and Read Holding Registers to handle communication.  This system worked well for several weeks with all PLCs being accessible and reporting correct instrument readings to the chassis which were then viewable through the main LabVIEW program and the test VI which is attached.  It was operating correctly Monday, after which I was out of the office for two days, and came back to find the following error displayed on each Read Holding Registers VI attempt:

Error -1073807254 occurred at Property Node (arg 1) in SubVIs.lvlib:RTU Data Unit.lvclass:Read ADU Packet.vi:5030001->Modbus Master.lvclass:Read Holding Registers.vi:2420001->TestMain.vi

Possible reason(s):

VISA:  (Hex 0xBFFF006A) A parity error occurred during transfer.

Sometimes I get this error displayed on the Create Master Instance VI attempt:

Error -1073807254 occurred at Property Node (arg 1) in SubVIs.lvlib:Serial Shared Components.lvlib:Configure Serial Port.vi->SubVIs.lvlib:Serial Master.lvclass:Initialize Master.vi->Modbus Master.lvclass:Initialize.vi->Modbus Master.lvclass:Create Master Instance (Serial).vi->TestMain.vi

Possible reason(s):

VISA:  (Hex 0xBFFF006A) A parity error occurred during transfer.

I've confirmed port settings on the PLC and on the CRio to be RTU, 38400, 1, Odd, None.  Changing these settings or disconnecting a wire from the DTech converter gives expected error messages in LabVIEW.

From the computer, I still have communication with the cRio through the provided USB cable and the analog modules are working properly in response to commands sent via the LabVIEW programs.  I have determined that the PLC and  

Modbus two-wire is working properly up to the point of the DTech converter.  I have also replaced the DTech converter with a new unit.  The LabVIEW programs have not changed since they were working on Monday and I reset and reinstalled the software on the cRio with no effect.  I have not been able to determine whether the computer's operating system was updated since Monday, but it is unlikely since it has been turned off during that time.  It is a Windows 10 64 bit machine.

The VI is attached.  Notably, I receive the same error message whether on the Read Holding Register VI or the Read Device Identification VI (not shown).

Any thoughts on this one?

[Paratore · Accepted solution]

Please disregard.  Apparently, one of the PLCs had a malfunction and was sending random bits across the network that were disrupting communications.  I'm not sure why this was impacting only the cRio and not my other attempts at Modbus communication using my PC, but removing the PLC from the system resolved the problem.

[YumingSu]

Hi.I met a similar error1073807254.Sounds like you just remove the PLC.Do you mean you replaced another one?I am quite confused about this problem.Could you tell me more details?It looks like a programming problem.