User manual

IEC61131 User and Reference Manual
April 22, 2008
384
Store and Forward Messaging
Store and forward messaging re-transmits messages received by a controller. Messages
may be re-transmitted on any serial port, with or without station address translation. A user-
defined translation table determines actions performed for each message. The Store and
Forward Messaging section below describes this feature in detail.
Store and forward messaging may be enabled or disabled on each port. It is disabled by
default.
I/O Database
The TeleBUS protocols read and write information from the I/O database. The I/O database
contains user-assigned registers and general purpose registers.
User-assigned registers map directly to the I/O hardware or system parameter in the
controller. Assigned registers are initialized to the default hardware state or system
parameter when the controller is reset. Assigned output registers do not maintain their
values during power failures. However, output registers do retain their values during
application program loading.
General purpose registers are used by ladder logic and C application programs to store
processed information, and to receive information from remote devices. General purpose
registers retain their values during power failures and application program loading. The
values change only when written by an application program or a communication protocol.
The I/O database is divided into four sections.
 Coil registers are single bits which the protocols can read and write. Coil registers are
located in the digital output section of the I/O database. The number of registers depends
on the controller. Coil registers are numbered from 1 to the maximum for the controller.
 Status registers are single bits which the protocol can read. Status registers are located
in the digital input section of the I/O database. The number of registers depends on the
controller. Status registers are numbered from 10001 to the maximum for the controller.
 Input registers are 16 bit registers which the protocol can read. Input registers are located
in the analog input section of the I/O database. The number of registers depends on the
controller. Input registers are numbered from 30001 to the maximum for the controller.
 Holding registers are 16 bit registers that the protocol can read and write. Holding
registers are located in the analog output section of the I/O database. The number of
registers depends on the controller. Holding registers are numbered from 40001 to the
maximum for the controller.
Accessing the I/O Database
TelePACE ladder logic programs access the I/O database through function blocks. All
function blocks can access the I/O database. Refer to the TelePACE Ladder Logic
Reference and User Manual for details.
ISaGRAF applications access the I/O database through dictionary variables with assigned
network addresses or using Permanent Non-Volatile Modbus registers. See the ISaGRAF
User and Reference Manual for details.
C language programs access the I/O database with two functions. The dbase function reads
a value from the I/O database. The setdbase function writes a value to the I/O database.
Refer to the TelePACE C Tools Reference and User Manual for full details on these
functions.