User manual

Chapter 6
PLC-5/VME Processor
Communications Commands
6-12
Data types are those resident in the PLC-5/VME processor. In the
typed-write and typed-read commands described in this chapter, each data
type has a code representing its ID. The data-type code is stored in byte
field “a” of the command or reply. Some data types have a corresponding
size. The data-type size is the number of bytes required to store one
element of the data type.
The field that stores the data-type ID and size codes has a default length of
one byte for ID and size codes 3-7. When the code exceeds 7, additional
bytes are appended to the default byte to specify ID and size. We describe
this in Table 6.B and Table 6.C.
T able 6.B
Data-Type Field Specified in Default Byte
ID Code Data Type
Description
Abbr. Size
p
3 A 1 ASCII
4 N, S, I, O 2 Integer (signed, two’s complement)
includes status and I/O data
5 T 10 A-B timer
6 C 6 A-B counter
7 R 6 A-B control
T able 6.C
Data-Type Field Specified in Appended Bytes
ID Code
Data Type
Description
Abbr. Size
p
8 F 4 Floating point (IEEE single precision)
9 – – Array (specifies data type and size)
10-15 – – Reserved
16 D 2 BCD
Important: If you want to write one element of a data type per packet,
select any of the standard data-type codes such as for integer, timer,
counter, control, or floating point. If you want to write multiple elements
of the same data type per packet, select the data-type code for the array.
You specify the data-type and size codes of any standard data type in
the array.
Data Types