User`s manual

XP8000 Series (PLCBus
TM
) Z-World 530-757-3737 19
the quadrature decoder/counter, and the control register. The
address of a particular SMC is determined by jumpers on H4:
abcd1100 x0000Rxx
a = 0 if H4 pins 1 and 2 are connected, and 1 if not
b = 0 if H4 pins 3 and 4 are connected, and 1 if not
c = 0 if H4 pins 5 and 6 are connected, and 1 if not
d = 0 if H4 pins 7 and 8 are connected, and 1 if not
x = don’t care
R = 0 to read or write the PCL-AK pulse generator
R = 1 to read the quadrature counter
R = 1 to write the control register
The LED (D2) will light when the SMC board is addressed.
Software keeps information for all SMCs on the PLCBus in a
table, sorted by SMC address. Thus, SMC boards have logical
addresses which are simply indexes into the table.
Reset States
There are many ways to reset the SMC and its components.
Power-Up Reset
On power-up, both the PCL-AK and the quadrature decoder/
counter undergo a hard reset.
The control register powers-up to an unknown state, thus your
application program should initialize it before using anything
else on the board.
PLCBus Reset
A PLCBus reset command strobes both the PCL-AK and
quadrature decoder/counter reset lines, forcing hard resets for
both. The control register and motor driver are not effected by a
PLCBus reset.
Watchdog Reset
The watchdog timer is a safety feature that halts the PCL-AK
(and therefore, motion) in the event of a system crash. When
you turn on the watchdog, your software must periodically
“hit” the watchdog at least every 1.5 seconds. The quadrature
counter is not reset in the event of a watchdog timeout.
Once reset this way, the PCL-AK will stay reset until your soft-
ware hits the watchdog again. Connecting the jumper J1 en-
ables the watchdog function. When it is unconnected, a watch-
dog reset will not occur.
PCL-AK Reset
Aside from the watchdog reset and power-up reset, there are
two other ways to reset the pulse generator.
To achieve a soft reset, write a reset command to the controller.
A soft reset immediately stops pulse generation and deactivates
the PCL-AK’s interrupt request line if it is active. The contents
of PCL-AK registers are not affected.
To achieve a hard reset, drive the PCL-AK reset line low.
Quadrature Counter Reset
The quadrature counter is reset to zero on power-up.
PCL-AK Formulas
The ADR—a register with settings from 2 to 1023—governs
ramping-up (acceleration) and ramping-down (deceleration)
characteristics. When started in high-speed mode, the PCL-AK
starts with the speed set on FL register and accelerates to reach
the speed set in the FH register.
The Z-World reference clock frequency is 6 MHz. The clock pe-
riod is 1/6 µs. The time it takes to accelerate or decelerate is
T
RAMP
= ( FH – FL ) × ADR / 6, in microseconds.
The relationship between acceleration and the ADR is this:
accel =
CLOCK
ADR
[ pulses / second
2
]
The relationship between the value of a speed register (FL or
FH) and actual output frequency is
freq
HIGH
=
FH
8192
[ pulses / sec ]
CLOCK
MUL
×
freq
LOW
=
FL
8192
CLOCK
MUL
× [ pulses / sec ]
The term MUL is the value of the multiplier register. It can be
from 2 to 1023.
Referring to the picture below, the number of pulses output
during T
DEC
is represented by the area of the shaded trapezoid:
ramp-down point
FH
FL
Rate
T
DEC
Time
P
DEC
= [ pulses ]
(freq
HIGH
+ freq
LOW
) × T
DEC
2
or
P
DEC
= [ pulses ]
(FH
2
–FL
2
) × ADR
16384 × MUL
The speed registers (FH and FL) have values from 1 to 8191.
The reference clock (on the CLOCK pin) is divided by the vari-
able frequency divider and multiplied by the frequency multi-
plier then output to /PULSE. The actual pulse frequency is
given here again:
freq =
F
X
8192
[ pulses / sec ]
CLOCK
MUL
×
= F
X
× factor [ pulses / sec ]
When factor = 1, output pulse frequency is the same as the con-
tents of the speed register (either FL or FH). With Z-World’s
6MHz reference clock, MUL = 732 (actually, 732.421875
rounded off) gives a factor close to 1, but not exactly.
Specifications
Board Size 2.835 × 4.0 × 0.58
Operating Temp –40°C to +70°C
Humidity 5% to 95% non-condensing
Power
24VDC, 40 mA
Provides One-axis stepper motor control rated at 35V
and 1.25A per phase in full step mode, and 1
amp per phase in half-step mode.