ElmoMC SimplIQ Software Manual - Manual (Page 109)

SimplIQ Software Manual Development Aids
MAN-SIMSW (Ver. 1.4)
7-13
The data is uploaded in hexadecimal form in order to minimize transmission time (relative
to ASCII formatted text), while adhering to the ASCII nature of transmissions. Each data
byte is parsed into two nibbles, and the ASCII code of the nibbles is sent from the controller
to the host. For example, the short integer number 43794 has the hexadecimal representation
AB12. It will be transmitted as “A” “B” “1” “2” with the most significant nibble first and the
least significant nibble last. The long integer number 1 will be sent as: “0” “0” “0” “0” “0”
“0” “0” “1”.
In order to analyze the BH record, it is important to understand that the internal
representation of quantities in the controller is not in user units. For example, while the user
relates to motor current in amperes, the controller represents current internally by the bits of
the A/D that measures the current. The BH record uploaded recorded currents (and other
variables as well) in their internal representation units, and also provides the scaling
multiplier to relate it to user units. This way, no multiplication inaccuracies are introduced
to the BH records, and the CPU load is minimized.
The recorded transmitted by the controller in response to a BH=n command is described in
the following table. The record includes 20 bytes of overhead, and numerical record data.
The variables in the table are translated into ASCII as described previously.
Byte
Number
Description
Value
Type
0 - 1 Variable type for user.
Field has no practical
significance. 0: Integer system parameter
1: Real system parameter
2: Integer user program
variable
3: Real user program variable Byte
2 - 3 Data width: number of hex
character of single transmitted
data item. 4: Short integer
8: Long integer Byte
4 - 7 Data length: actual number of
transmitted data items. Word
8 - 11 Variable time multiplier:
number by which TS must be
multiplied to obtain basic
recording period. Depends on RP[0] value Word
12 - 19 Floating number factor, by
which every uploaded data item
is multiplied in order to convert
it to user units, such as amperes,
or counts/second. 32-bit float
number in
IEEE
format.
20 - 20+ (Data length) * (Data width) -1:
data items. Oldest record is
transmitted first, and most
recent record is transmitted last.
Words or
long
integers,
according
to data
width.
Table 7-7: BH Record Structure