Table 1

Table 2

Relay X & Y

Input relay X

The input relay X represents the physical inputs to PLC. It could detect the external signal states. 0 is for open circuit, 1 is for closed circuit.

The states of input relays couldn’t be modified by program instruction, the node signal (normally open, normally closed) could be unlimited use in the program.

If connected IO expansion module, the port starts from the main module, according to the order of the numbers. But DI is named in groups of eight. For example main module is X0~X7, X10~X14. The X0 in DI expansion module corresponds to X20, not X15.

Devices numbered in: Octal, i.e. X0 to X7, X10 to X17

 [Available devices]

Table 1

Output replay Y

The output relay Y represents physical outputs from PLC. 0 is for open circuit, 1 is for closed circuit.

Depending on the output element could be divided into relay type, transistor type etc.

If connected IO expansion module, the port starts from the main module, according to the order of the numbers. But DO is named in groups of eight. For example main module is Y0~Y7, Y10~Y14. The Y0 in DO expansion module corresponds to Y20, not Y15.

Devices numbered in: Octal, i.e. Y0 to Y7, Y10 to Y17.

Relay M

Auxiliary Relay M device is used as an intermediate variable during the execution of a program, as auxiliary relays in the practical power control system which is used to transfer the state messages. It could use the word variable formed by M variables. M variables is not directly linked with any external ports, but it could contact with the outside world by the manners of copying X to M or M to Y through the program coding. A variable M could be used repeatedly.

Devices numbered in: Decimal, i.e. M0 to M9, M10 to M19. The variables that are more than M8000 are the system-specific variables, which are used to interact with the PLC user program with the system states; part of the M variables have the feature of power-saving.

General stable state suxiliary relays

The general stable state Auxiliary relays in LX3V series PLC are M0 ~ M499, there are total of 500 points. The type of auxiliary relay is related to its part number and PLC serial.

Table 1

Users could set non-latched and latched area for Auxiliary relays in PLC by parameter setting

※1, Non-latched area, it could be changed to latched area by parameter setting.

※2, Latched area, it could be changed to non-latched area by parameter setting.

※3, The non-latched or latched feature couldn’t be changed.

Latched auxiliary relays

There are a number of latched relays whose state is retained. If a power failure should occur all output and general purpose relays are switched off. When operation is resumed the previous state of these relays is restored.

As below pictures show, in (a), relay M500 is activated when X0 is turned ON. If X0 is turned OFF after the activation of M500, the ON state of M500 is self-retained. (b) shows Circuit Waveform diagram of (a). For using this function, (c) could makes M500 “Turn ON” all the time. 

System-specific auxiliary relays

A PLC has a number of special auxiliary relays. These relays all have specific functions such as provide clock pulse and sign, set PLC operation mode, or use for step control, prohibit interrupt, set counter is adding count or subtract count, etc. And they are classified into the following two types.

• Using contacts of special auxiliary relays, coils are driven automatically by the PLC. Only the contacts of these coils may be used by a user defined program.
  Examples:
  • M8000: RUN monitor (ON during run);
  • M8002: Initial pulse (Turned ON momentarily when PLC starts);
  • M8012: 100 msec clock pulse;

• Driving coils of special auxiliary relays, a PLC executes a predetermined specific operation when these coils are driven by the user.

          Examples:

• 
  
  • M8033: All output statuses are retained when PLC operation is stopped;
  • M8034: All outputs are disabled;
  • M8039: The PLC operates under constant scould mode;

Relay S

State relays S is used to design and handle step procedures, controls transfer of step by STL step instructions to simplify programming design. S also could be used as M, if there is no STL instruction. Part of the S has the feature of power-saving.

Devices numbered in: Decimal, i.e. S0 to S9, S10 to S19.

Table 1

※1, Non-latched area, it could be changed to latched area by parameter setting.

※2, Latched area, it could be changed to non-latched area by parameter setting.

※3, The non-latched or latched feature couldn’t be changed.

General State Relays

As above picture shows, when X0=ON, then S0 set ON, and Y0 is activated. When X1=ON, then S11 set ON, and Y1 is activated. When X2=ON, S12 set ON, then Y2 is activated, as Figure 3-2 shows.

Latched State Relays

There are a number of latched relays whose state is retained. If a power failure should occur all output and general purpose relays are switched off. When operation is resumed the previous state of these relays is restored.

Figure 2

Annunciator Flags

Some state flags could be used as outputs for external diagnosis (called annunciation) when certain applied instructions are used.

If X1 and X2 set ON at the same time and keep more than 1 seconds, S900 is activated, if X1 or X2 is turned OFF after the activation of S900, the ON state of S900 is self-retained. If X1 and X2 set ON at the same time less than 1 seconds, S900 is not activated.

Timer

The timer is used to perform the timing function. Each timer contains coils, contacts, and counting time value register. A driven coil sets internal PLC contacts. Various timer resolutions are possible, from 1 to 100ms. If the coil power shuts off (insufficient power), the contacts will restore to their initial states and the value will automatically be cleared. Some timers have the feature of accumulation and power-saving.

Devices numbered in: Decimal, i.e. T0 to T9, T10 to T19.

Table 1

General timer (T0~T245)

The timer output contact is activated when the count data reaches the value set by the constant K.

Figure 2

As above picture shows, when X0 is on, T200 counts from zero and accumulates 10ms clock pulses. When the current value is equal to the set value 223, timer output contact is activated; the output contact of the T200 is actuated after its coil is driven by 2.23s.

Retentive Timers (T246~T255)

Figure 3

As above picture shows, T250 has the ability to retain the currently reached present value even after X1 has been removed. If T1+T2=42s, T250 (open contact) set on. When X2 set ON, timer T250 will be reset.

Set value

The set value of the timer could be determined by constant (K, H) in the program memory and could also be specified indirectly with the contents of the data register (D).

As above program shows, D3 is set value for T10, D3=D0*2.

Counter

Counter

Counter performs counting function, it contains coil, contact and count value register. The current value of the counter increases each time coil C0 is turned ON. The output contact is activated when count value reach to preset value.

Counters which are latched are able to retain their status information, even after the PLC has been powered down. This means on re-powering up, the latched counters could immediately resume from where they were at the time of the original PLC power down.

Devices numbered in: Decimal, i.e. C0 to C9, C10 to C19

Table 1

※1, Non-latched area, it could be changed to latched area by parameter setting.

※2, Latched area, it could be changed to non-latched area by parameter setting.

※3, The non-latched or latched feature couldn’t be changed.

16bit up counter

16bit counters: 1 to +32,767, as below picture shows, the current value of the counter increases each time coil C0 is turned ON by X2. The output contact is activated when the coil is turned ON for the tenth time.

After this, the counter data remains unchanged when X2 is turned ON. The counter current value is reset to ‘0’ (zero) when the RST instruction is executed by turning ON X1 in the example. The output contact Y0 is also reset at the same time.

Figure 2

32bit bi-directional counter

32bit bi-directional counters: -2,147,483,648 to +2,147,483,647. C200- 219 are general, C220- 234 are latched.

The counting direction is designated with special auxiliary relays M8200 to M8234. When the special auxiliary relay is ON, it is decremented; otherwise, it is counting up.

High speed counter

Although counters C235 to C255 (21 points) are all high speed counters, they share the same range of high speed inputs. Therefore, if an input is already being used by a high speed counter, it could not be used for any other high speed counters or for any other purpose, i.e as an interrupt input.

The selection of high speed counters is not free, they are directly dependent on the type of counter required and which inputs are available.

• Available counter types

1. 1 phase with user start/reset: C235 to C240
2. 1 phase with assigned start/reset: C241 to C245
3. 2 phase bi-directional: C246 to C250
4. A/B phase type: C251 to C255

Different types of counters could be used at the same time but their inputs must not coin-cider. Inputs X0 to X7 couldnot be used for more than one counter.

Table 3

U: up counter input

D: down counter input

R: reset counter (input)

S: start counter (input)

A: A phase counter input

B: B phase counter input

Figure 4

As above program shows, C244 is 1 phase high speed counter with start, stop and reset functions. From the table, X1~X6 are for start and reset. C244 start counting when X12 and X6 are turned ON, the counter input terminal is X0, set value for C244 is determined by D0 (D1), so C244 could be reset by X0 or X11.

Figure 5

C251~C255 are 2 phase (AB phase) high speed counter. As above (b) picture shows, C251 counts according from X0 (A phase) and X1 (B phase), when X14 is turned ON. C251 is reset when X13 is turned ON.

While A phase is turned ON, if B changes state from OFF to ON, C251 executes up count operation. While A phase is turn ON, if B changes state from ON to OFF, C251 executes down count operation. According to this principle, C251 executes up count operation while machine forward, and C251 executes down count operation while machine reverse. The M8251 monitors the C251's up / down counting status, OFF is for up counting, ON is for down counting.

Output Y: high speed pulse output transistor

• It supports up to 4 channels, and each channel maximum output frequency is 200K;
• The output frequency could be used for controlling inverter, stepper and servo motors and so on;

Input X: one phase

• X0, X1 hardware counters (C235, C236, C246), could support 200K pulse input at the same time;
• X0, X1 software counters (C241, C244, C247, C249), could support the input of 100K pulses at the same time;
• The hardware counter could be switched to software counting using HSCS, HSCR, HSZ instructions;
• The last four X points are software counting, which could support the input of 10K pulses at the same time.

Input X: A/B phase

• X0, X1 hardware counter (C251), can support 100K pulse input;
• X0, X1 software counters (C252, C254) support the simultaneous input of 50K pulses at the same time;
• Hardware counter can be switched to software counter, using HSCS, HSCR, HSZ instructions;
• The remaining X points are counted by software, and each 5K pulse frequency can be input at the same time;
• There are two frequency modes for 2 phase 2 input, one is 2 times, and the other is 4 times, as following table shows, users select mode in D8200;

Table 6

Program example2: AB encoder

Register D

Data registers, as the name suggests, store data. The stored data could be interpreted as a numerical value or as a series of bits, being either ON or OFF. A single data register contains 16bits or one word. However, two consecutive data registers could be used to form a 32bit device more commonly known as a double word. If the contents of the data register are being considered numerically then the Most Significouldt Bit (MSB) is used to indicate if the data has a positive or negative bias. As bit devices could only be ON or OFF, 1 or 0 the MSB convention used is, 0 is equal to a positive number and 1 is equal to a negative number.

In WECON LX Series PLC, most data in the instructions are signed numbers. The bit 15 in 16-bit address is sign bit (0 means positive, 1 means negative). The high bit 15 in 32-bit address is sign bit, the data range is -32,768 - +32,767.

Devices numbered in: Decimal, i.e. D0 to D9, D10 to D19

※1, Non-latched area, it could be changed to latched area by parameter setting.

※2, Latched area, it could be changed to non-latched area by parameter setting.

※3, The non-latched or latched feature couldnot be changed.

General

A single data register contains 16bits or one word. However, two consecutive data registers could be used to form a 32bit device more commonly known as a double word. Data remains the same until the next time it is rewritten. When switch the PLC state (RUN to STOP or STOP to RUN), the data will be erased. If the special auxiliary relay M8033 is ON, the data in general data register will be retained while switch PLC state.

Latched

The data in register will be retained while switch PLC state. The latched register range could be modified by parameters.

System-special

System-special data register D8000 ~ D8255 are used for controlling and monitoring a variety of work methods and components in PLC, such as battery voltage, scould time, and is the state of action and so on. The default value will be written into those registers while PLC power on.

Index registers V, Z

The index registers are same as common data registers, is 16-bit registers for data reading and writing. There are totally 64 registers, V0-V31, Z0-Z31.

The index registers could be used in combination with other registers or values by application instructions. But they couldnot be used in combination with the basic instructions and step ladder diagram instruction.

File registers D

The file registers start from D1000 to D7999. File registers could be secured in the program memory in units of 500 points. File registers are actually setup in the parameter area of the PLC. For every block of 500 file registers allocated and equivalent block of 500 program steps are lost.

Register P, I

Pointers register P is used for entry address of jump program, and identification of sub-program starting address.

Pointer register I is used for identification of interrupted program starting address.

Devices numbered in: Decimal, i.e. P0 to P9, P10 to P19, I0 to I9, I10 to I19.

1. Sub-program pointer

As below demos show, the left one is for conditional jump with [CJ] instruction, the right one is for Sub-program call with [CALL] instruction.

Interrupt pointer

An interrupt pointer and various usage of three, dedicated interrupt applied instructions;

• IRET: interrupt return
• EI: enable interrupt
• DI: disable interrupt

Usage of interrupt

• Input Interrupt: Receive signals from a particular input without being affected by the scould cycle of PLC;
• Timer Interrupt: The interrupt is repeatedly triggered at intervals of the specified time (10ms~99ms);
• Counter Interrupt: The interrupt is triggered according to the comparison result of the built-in high-speed counter of PLC;

LX Series PLC could support five kinds of contacts for programming, the detailed as the following table shows.

Constant K

[K] is decimal integer symbol, mainly used for setting the value of the timer or counter or application instruction operand values. The value range in 16-bit is -32,768 – 32,767, the value range in 32-bit is -2, 147,483, 648 – 2, 147, 483, 647.

Constant H

[H] is hexadecimal numbers symbol, mainly used for setting the value of application instruction operand value. The value range in 16-bit instruction is 0000-FFFF, the value range in 32-bit instruction is 0000, 0000– FFFF, FFFF.

Constant E

[E] is single-precision floating symbol, mainly used for setting the value of application instruction operand value. It is only available in DECMP、DEZCP、DSINH、DCOSH、DTANH、DEBCD、DEBIN、DEADD、DESUB、DEMUL、DEDIV、DEXP、DLOGE、DLOG10、DESQR、DINT、DSIN、DCOS、DTAN、DASIN、DACOS、 DATAN、DRAD、DDEG instructions in LX3VP and LX3VE series. The value range is ±1.175495 E-38～±3.402823 E+38.

System-special address