modbus: Modbus Support - Release Notes
Release 2-2
March 13, 2011
- R2-0 introduced a 20 ms delay before each Modbus write. This was not correct,
delays should only be needed for serial RTU. The Modicon Modbus Protocol Reference
Guide says this must be at least 3.5 character times, e.g. about 3.5ms at 9600 baud,
for Serial RTU. An additional writeDelayMsec parameter was added to modbusInterposeConfig.
It is the final parameter, so if it is not specified the default value is zero,
which is appropriate when not using Serial RTU. In the startup script lines like
the following:
modbusInterposeConfig("Koyo1",0,5000)
should be changed to:
modbusInterposeConfig("Koyo1",0,5000,0)
for no delay, or to:
modbusInterposeConfig("Koyo1",0,5000,20)
for a 20 ms delay.
Release 2-1
November 7, 2010
- Bug fix. Non-automatic connection to the Modbus server uses pasynCommonSyncIO->connectDevice().
The pasynUser being used for that operation was being created with pasynOctetSyncIO->connect().
That was always an error, it must be created with pasynCommonSyncIO->connect().
This error became serious with asyn R4-14, and non-automatic connection no longer
worked.
- Previous releases of modbus recommended setting NoAutoConnect=1 when configuring
the TCP or serial port. That was probably because of problems in connection management
in earlier versions of asyn. With asyn R4-14 this is no longer necessary, and NoAutoConnect=0,
the normal default, can be used with no problems. The example scripts Koyo1.cmd
and Koyo2.cmd in the iocBoot directory have been changed to enable automatic connection
to the IP or serial driver.
Release 2-0
November 26, 2009
- Moved the slave address handling from the asynInterpose layer to the Modbus driver
layer. This was done because handing it in the the interpose layer only allowed
1 slave address per asyn serial port or IP port. This did not allow a single serial
port to be used with multiple Modbus devices on an RS-485 bus, for example. NOTE:
This requires all startup command scripts to be changed, because the syntax of the
modbusInterposeConfig and drvModbusAsynConfigure commands has changed. Thanks
to Yves Lussignol from CEA in France for making these changes.
Release 1-3
September 19, 2008
- Changed modbusInterpose.c to replace pasynOctet->writeRaw() and pasynOctet->readRaw()
with pasynOctet->write() and pasynOctet->read(), because the raw routines have been
removed in asyn R4-10.
- Changed the driver to use the asynStandardInterfaces interfaces added to asyn
in R4-10.
Release 1-2
September 6, 2007
- Fixed bug in computing byteCount in WRITE_MULTIPLE_COILS function code.
There is a known limitation with using serial interfaces. It is not currently possible
to have multiple Modbus servers connected to a single serial port. This is a limitation
of the asynInterposeInterface architecture used. It is fixed in release 2-0.
Release 1-1
April 30, 2007
Initial release of modbus module.