1. Overview of high speed counter
21 C235~C255 share PLC high-speed counter 8 high-speed counter inputs X0~X7, an input at the same time can only be used for a high speed counter. 21 counters are 32-bit plus/minus counter (see table 3-7). Different types of counters can be used simultaneously, but their high speed counter input cannot conflict.
Run based on the interruption of high speed counter, this means that the trigger has nothing to do with the scan time. External pulse counting at high speed, high speed counter in the ladder diagram coils should always be powered on, to express it-related entry point is already in use, and other high speed counter cannot conflict with it. Runtime has been available ON the M8000 normally open to drive high speed counter coil.
For example, in Figure 1, when X14 is ON, and select high speed counter C235, from tables 3 – 7, C235 counting input is X0, but it does not appear in the program, count signals are not provided by X14.
Table 1 shows the various components of high speed counter input terminal number, u, d in the table respectively, addition, subtraction counting input a, b a, b input respectively, r for reset input, s is the set input.
2. A high speed counter
C235~C240 for a no start/reset input high-speed counter, C24l~C245 is a high speed counter with reset start/end, M8235~M8245 can be used to set the counting direction C235~C2415 and m is ON when count reduction, OFF to add count. C235~C240 can only be reset with RST command.
C244 in Figure 1 are 1 high speed counter with reset start/end, table 1 shows that the Xl and X6, respectively, for the reset input and start inputs, reset and start with a scan of their work has nothing to do, its effect is immediate and direct. If X12 is ON, once the X6 ON, immediately began counting, counting input is X0. X6 OFF, stop counting, C244 value specified by the D0 and D1. Except Xl to immediately reset, but can also be used in the ladder diagram reset instructions reset.
3. two phase bi-directional counters
Two-phase two-way counter (C246~C250) has a add count input and a reduced count input, such as add, subtract counts C24
6 inputs X0 and Xl, respectively, at the counter when the coil is energized, X0 rising edge, the counter's current value plus 1, X1 rising edge, the counter's current value l. Some counters are reset and start input
4. A-B is double-counting input high-speed counter
C25l~C255 for double counting in a-b input high-speed counter, they have two counting inputs, some counters are reset and start input.
Figure 2 when X12 is ON, C25l interrupted, a believe to X0 input and X1 action count input b signal. C251 is reset when X11 is ON, when the count value is greater than or equal to the set value, Y2 the coil is energized, if the count is less than the given value, coil power Y2.
A/B not only provides a count signal input, based on their relative phase relationships, counting direction is also provided. A/B encoder installed on the axis in the machinery is transferred automatically when you add count, count down automatically when the reverse. When you enter ON a phase, phase b input from OFF to ON, and count (see Figure 2B); a phase ON time, if phase b from ON to OFF, to reduce count (see figure 2c). M8251 monitors the C251 plus/minus count, and count M8251 is OFF, count M8251 ON reduction.
5. High speed counter counting speed
General count frequency: single and bi-directional highest counter l0kHz,A/B counter top is 5kHz.
Maximum total count frequency: FXlS and FXlN-60kHz,FX2N and FX2NC-20kHZ, when calculating the total number of frequency A/B frequency counter should be doubled. FX2N, FX2NC, X0 and X1 with special hardware, for single or double counting (C235,C236 or C246) up to 60kHz, C25l two-phase counts up to 30kHz.
Application instructions SPD (speed, FUC56) has the characteristics of high speed counter and enter the break, X0~X5 may be used by SPD instruction, SPD instructions using the entry point cannot be entered for use with high speed counter and interrupt conflicts. High-speed counters total count rate, the SPD directive should be considered as l high speed counter.