Varec 8300 series, Installation And Operation Manual, Page: 80 / 150

Tank Gate Interface
70 Installation and Operations Manual
5.8.2 Application
The MFPREG point continually scans Modbus slave devices, using the ID parameter. Chan
determines which 8203 Dual RS-485 Communications Interface Module Channel is used for
communications to the slave device. An MFPREG point is needed for each device connected to
the 8303 TGI. Up to 64 registers may be read with each MFPREG point. Multiple MFPREG points
can be used with a single slave device if necessary. The BaudRate and ComParams values must
match the communications parameters of the slave device. The communications parameters are
set as each MFPREG point is processed. This allows slaves with different baud rates and data link
settings to exist on the same bus (not recommended).
8203 TGI software points may begin scanning when the point is created, or when the correct
Channel number is assigned. Which of these events begins the scanning process varies with
each point.
A total of four blocks may be read or written. The ReadCmd determines the command to read
data and the WriteCmd is the command used for write operations. The Addr and Size parameters
determine the addresses. Set the Addr1 and Size1 parameters to read a data block from the slave
device. The response will be placed in the Value0 - Value63 parameters. For example, if Addr1
= 100 and Size1 = 10, then the MFPREG point will read 10 register values and place the data in
Value0 - Value9. If a second block is defined, then the data response will start in Value10. If the
Size is 0, then that block is disabled.
The Mode parameter can be used to swap the byte order of the floating point values.
Dynamic Parameters Function
Value0
Value63 Register values from slave device. Value0 will always correspond to the
first register read from the slave device using the Addr1 and Size1
parameters. You can read up to 64 registers from the slave device. The
meaning of the Value array depends upon the definition of the blocks.
PntStatus Byte value indicating status of point Values are:
0x0000: No Error
0x0001: No Response from Device
Elapse Time of the last request from the master
PntCheckSum CRC-16 Checksum of point's static Configuration Parameters