User manual

IEC61131 User and Reference Manual
April 22, 2008
407
Preset Multiple Registers
The Preset Multiple Register function writes 16 bit values into holding registers of the remote
device. The data may come from the analog input or output sections of the I/O database.
Any number of registers may be written up to the maximum number supported by the slave
device or the maximum number above, which ever is less. The write may start at any
address, provided the entire block is within the valid register range of the remote device.
Each register is 16 bits.
Enron Modbus Master Mode
The Enron Modbus protocol is based on the Modbus ASCII and RTU protocols. Message
framing is identical to the Modbus protocols. However, there are many differences in
message formatting and register numbering, at both the logical and protocol levels.
The document Specifications and Requirements for an Electronic Flow Measurement
Remote Terminal Unit describes the Enron Modbus protocol.