Publication 1766-RM001A-EN-P - October 2008
238
Application Specific Instructions
The RHC instruction provides a high performance timestamp for
diagnostics and calculation such as velocity. The controller maintains a 10
µs long integer free running clock/counter. This 32 bit value increments
every 10 µs after power-up
Enter the following parameters when programming this instruction:
•
Destination is the address to store the current value of the 10 µs free
running clock. It can be an integer address, long integer address or
Float address.
Instruction Operation
This instruction executes on a true rung. When the rung is true, this
instruction moves the current value of the 10 µs free running clock into
the Destination.
If the Destination is an integer address type, only 16 bits are moved into
the address. If the Destination is floating point address, the long integer
value is converted into a float and is moved the relative address.
After the free running clock reaches 0xFFFFFFFF (42949.67295 seconds)
value, it wraps around to 0 and continues incrementing. The RESET signal
or Power Cycle sets the free running clock to 0.
RHC Instruction Valid Addressing Modes and File Types
For definitions of the terms used in this table see Using the Instruction Descriptions on page 92.
Parameter
Data Files
Function Files
(1)
C
S
-
Comms
IO
S - I/O
DL
S
-
D
a
ta
L
o
g
(2
)
Address Mode
(3)
Address Level
O
I
S
B
T,
C
, R
N
F
ST
L
MG, PD
R
I/RIX
PL
S
RT
C
HS
C
PT
OX
, P
W
M
X
ST
I
EII
BH
I
MM
I
LC
D
Dir
ect
In
di
re
c
t
Immediate
In
t1
6
Immed
iate Int32
Immed
iate Float
Bi
t
Wo
rd
Dou
b
le
W
o
rd
Elemen
t
Fl
o
a
t
Destination
•
•
•
•
(1) PTOX and PWMX files are only for use with MicroLogix 1400 BXB or BXBA unit.
(2) The Data Log Status file can only be used for the following math instructions: ADD, SUB, MUL, DIV, NEG, and SCP.
(3) See Important note about indirect addressing.
IMPORTANT
You cannot use indirect addressing with: S, MG, PD, RTC, HSC, PTOX,
PWMX, STI, EII, BHI, MMI, CS, IOS, and DLS files.
efesotomasyon.com - Allen Bradley,Rockwell,plc,servo,drive
