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4 Modbus Communications Procedure
E5C-T Digital Temperature Controllers Programmable Type Communications Manual (H186)
4-3 Variable Area
4
4-3 Variable Area
The variable area is the region of memory used to exchange data with the E5@C-T through communi-
cations.
Operations such as reading the process value and reading/writing parameters are performed on the
variable area.
On the other hand, operation commands do not use the variable area.
When accessing the variable area, the position of a variable in the variable area is specified with a word
identifier, area number, and address in the area.
Addresses
An address is appended to each of the variable types. Express addresses in 2-byte hexadecimal
and append them for the specified access size.
Number of Elements
The number of elements is expressed in 2-byte hexadecimal. The setting range for the number of
elements varies according to the command.
Four-byte Mode
One element uses 2 bytes of data, so specify two-element units. Reading and writing in 4-byte units
is executed by specifying an even address and specifying the number of elements in multiples of 2.
Two-byte Mode
One element uses 2 bytes of data, so specify one-element units. Reading and writing in 2-byte data
units is executed by specifying 1-element units.
Set Values
The values read from the variable area or written to the variable area are expressed in hexadecimal,
ignoring the decimal point position. (Negative values are expressed in 2's complement format.)
Example: D'105.0 → H'0000041A
The variables are 4-digit or 8-digit hexadecimal values. Negative values are expressed in 2's
complement format. The values are hexadecimal values with no decimal point indication.
For example, if the E5@C-T's process value is read in 4-byte mode when the process value is 105.0,
the read value will be H'0000041A (105.0 → 1050 → H'0000041A).
However, values that are read or written when the unit is hours:minutes, minutes:seconds, or
days:hours will be in BCD, the same as the display values.
Example, if 99.59 is displayed, the set value is H'00009959.
E5
@
C-T
Operation
commands, etc.
Read/write
Microcomputer
Variable area
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