Re: Modbus Module issue

[Luis Alberto De Sousa Moreira via Tech-talk <tech-talk at aps.anl.gov>]

    Hi  Jörn,
    I think we getting the wires crossed here... the OPCUA port is 4840
    but the 502 port is the normal Modbus port. 
    I managed to connect fine to it with other applications in the same
    machine.

    Kind Regards
                      Luis

On 24/07/2026 10:38, Jörn Dreyer wrote:

> Hi Luis,
>
> are you sure you are using the correct port?
> The Beckhoff documentation tells that the OPCUA server is listening on port 4840.  Did you cahnge that when installing the OPCUA Sever on the PLC?
> The Ports 500 + x are normally used for the various NC applications in your PLC program.
>
> Regards
>
> Jörn
>
> Am Freitag, 24. Juli 2026, 09:57:38 Mitteleuropäische Sommerzeit schrieb Luis Alberto De Sousa Moreira via Tech-talk:
> > Just found another application I used before as a Modbus client, called 
> > EasyModbusClient.
> > It connects fine and gets data.
> >
> > This is getting more intriguing...
> >
> > Best Regards
> >                    Luis
> >
> > On 24/07/2026 09:40, Luis Alberto De Sousa Moreira via Tech-talk wrote:
> > > Hi Gabriel,
> > > The firewall seems to be the culprit, but I added rules for the 
> > > application. I also just done a test where I disabled the firewall and 
> > > I get the same result.
> > >
> > > D:\FalconDev\EPICS\modbus\iocBoot\iocTest>..\..\bin\windows-x64-mingw\modbusApp.exe 
> > > BPS_Beck.cmd
> > > # BPS_Beck.cmd
> > > # Just testing the modbus module with my BPS Beckhoff PLC.
> > > # 1. Cleanly lock network routing automatically at boot
> > > epicsEnvSet("EPICS_CA_ADDR_LIST", "10.136.0.255")
> > > epicsEnvSet("EPICS_CA_AUTO_ADDR_LIST", "NO")
> > > epicsEnvSet("EPICS_CAS_INTF_ADDR_LIST", "10.136.0.34")
> > > # gvl.mb_Input_Registers[10] := GVL.d_setpoint_T1;              // T1  
> > >                  mS
> > > # gvl.mb_Input_Registers[11] := GVL.d_setpoint_TRamp1;  // Ramp1       
> > >         uS
> > > # gvl.mb_Input_Registers[12] := GVL.d_setpoint_v1;              // V1  
> > >                  10V
> > > # gvl.mb_Input_Registers[13] := GVL.d_setpoint_T2;              // T2  
> > >                  mS
> > > # gvl.mb_Input_Registers[14] := GVL.d_setpoint_TRamp2;  // Ramp2       
> > >         uS
> > > # gvl.mb_Input_Registers[15] := GVL.d_setpoint_V2;              // V2  
> > >                  10V
> > > # gvl.mb_Input_Registers[16] := GVL.d_setpoint_T3;              // T3  
> > >                  mS
> > > # gvl.mb_Input_Registers[17] := GVL.d_setpoint_TRamp3;  // Ramp3       
> > >         uS
> > > # gvl.mb_Input_Registers[18] := GVL.d_setpoint_V3;              // V3  
> > >                  10V
> > > # gvl.mb_Input_Registers[19] := GVL.d_setpoint_pulseLength;     // 
> > > PulseLength  S /mS
> > > # gvl.mb_Input_Registers[20] := GVL.d_setpoint_TRampDown;       // 
> > > RampDown             uS
> > > dbLoadDatabase("../../dbd/modbusApp.dbd")
> > > modbusApp_registerRecordDeviceDriver(pdbbase)
> > > # Get the connection going
> > > drvAsynIPPortConfigure("BPS_Beck", "10.136.0.30:502", 0, 0, 0)
> > > 2026/07/24 09:32:59.953 BPS_Beck -1 autoConnect could not connect: 
> > > Can't connect to 10.136.0.30:502: Unknown error
> > > # drvAsynIPPortConfigure("BPS_Beck", "8.8.8.8:8080", 0, 0, 0)
> > > modbusInterposeConfig("BPS_Beck", 0, 5000, 0)
> > > asynSetOption("BPS_Beck",0, "disconnectOnReadTimeout", "Y")
> > > # 
> > > =========================================================================
> > > # Configure Modbus Drivers Memory Blocks
> > > # 
> > > =========================================================================
> > > # Syntax:
> > > # drvModbusAsynConfigure("portName", "tcpPortName", slaveAddress, 
> > > modbusFunction, modbusStartAddress, modbusLength, dataType, pollMsec, 
> > > "plcType")
> > > # drvModbusAsynConfigure("modbusPortName", "asynPortName", 
> > > slaveAddress, modbusFunction, startAddress, length, dataType, 
> > > pollMsec, "plcType")
> > > # Read Coils (Function Code 1)
> > > # Reads 16 binary bits starting at offset 0, polling every 200 
> > > milliseconds.
> > > # drvModbusAsynConfigure("READ_COILS", "PLC_NET", 0, 1, 0, 1, 0, 200, 
> > > "OldPLC")
> > > # Write Coils (Function Code 5)
> > > # Configures a write-only path for coils. pollMsec is 0 because writes 
> > > are instantaneous.
> > > # drvModbusAsynConfigure("WRITE_COILS", "PLC_NET", 0, 5, 0, 1, 0, 0, 
> > > "OldPLC")
> > > # Reads 11 read-only 16-bit registers starting at offset 10, polling 
> > > every 500 milliseconds.
> > > # dataType=0 specifies standard 16-bit unsigned integers (UINT_16).
> > > drvModbusAsynConfigure("READ_INPUTS", "BPS_Beck", 1, 4, 10, 11, 0, 
> > > 500, "Beckhoff")
> > > # Read Holding Registers (Function Code 3)
> > > # Reads 1 read/write 16-bit register starting at offset 0, polling 
> > > every 500 milliseconds.
> > > # dataType=0 specifies standard 16-bit unsigned integers (UINT_16).
> > > # drvModbusAsynConfigure("READ_HOLDING", "PLC_NET", 0, 3, 0, 1, 0, 
> > > 500, "OldPLC")
> > > # Block E: Write Holding Registers (Function Code 6)
> > > # Configures a write-only path for single registers. pollMsec is 0 for 
> > > on-demand writing.
> > > # drvModbusAsynConfigure("WRITE_HOLDING", "PLC_NET", 0, 6, 0, 1, 0, 0, 
> > > "OldPLC")
> > > # Enable ASYN_TRACEIO_HEX on octet server
> > > # asynSetTraceIOMask("BPS_Beck",0,4)
> > > # Enable ASYN_TRACE_ERROR and ASYN_TRACEIO_DRIVER on octet server
> > > # asynSetTraceMask("BPS_Beck",0,9)
> > > dbLoadRecords("../../db/BPS_Beck.db")
> > > iocInit
> > > Starting iocInit
> > > ############################################################################
> > > ## EPICS R7.0.10
> > > ## Rev. 2026-07-01T08:47+0200
> > > ## Rev. Date build date/time:
> > > ############################################################################
> > > 2026/07/24 09:33:00.992 drvModbusAsyn::doModbusIO port READ_INPUTS 
> > > error calling writeRead, error=asynManager::queueLockPort queueRequest 
> > > failed: port BPS_Beck not connected, nwrite=0/6, nread=0
> > > iocRun: All initialization complete
> > > epics>
> > >
> > > Kind Regards
> > >                  Luis
> > >
> > >
> > >
> > > On 23/07/2026 16:24, Gabriel Fedel wrote:
> > > > Hi Luis,
> > > >
> > > > Couldn't the firewall be blocking  the EPICS application ?
> > > >
> > > > Best Regards
> > > > Gabriel
> > > > ------------------------------------------------------------------------
> > > > *From:* Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Luis 
> > > > Alberto De Sousa Moreira via Tech-talk <tech-talk at aps.anl.gov>
> > > > *Sent:* Thursday, July 23, 2026 3:59 PM
> > > > *To:* Mark Rivers <rivers at cars.uchicago.edu>; tech-talk at aps.anl.gov 
> > > > <tech-talk at aps.anl.gov>
> > > > *Subject:* Re: Modbus Module issue
> > > > Hi Mark,
> > > > My other application is using the Modbus protocol, I used it to do the
> > > > initial testing on my system.
> > > > I tried the telnet command from my MSYS2 environment and it can 
> > > > connect...
> > > >
> > > > telnet 10.136.0.30 502
> > > > Trying 10.136.0.30...
> > > > Connected to 10.136.0.30.
> > > > Escape character is '^]'.
> > > >
> > > > Kind Regards
> > > >                    Luis
> > > >
> > > > On 23/07/2026 15:31, Mark Rivers wrote:
> > > > > telnet 10.136.0.30 502
> > > > >             
> > > >
> > > >           
> > >         
> >       
>     
    
-- 
Luis Moreira
EPFL SB SPC-II, PPH241 (Batiment PPH) Station 13
CH-1015 Lausanne, Switzerland
Tel.    (+41) 21 693 58 37
E-Mail  luis.moreira at epfl.ch