modbus: Modbus Support - Release Notes

• 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.