modbus: Modbus Support - Release Notes

• 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.

• 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.

• 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.

• 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.

Initial release of modbus module.