6.14.1 RS instruction

Instruction description

RS is a transceiver instruction that automatically sends the data stored in the specific register to the serial port sequentially and stores the data received by serial port in the specific area. It is equivalent to directly access the communication buffer.

COM2 (communication port): it uses RS485, it supports program protocol (PLC protocol), MODBUS protocol (MODBUS-RTU slave, MODBUS-RTU master, MODBUS-ASCII slave, MODBUS-ASCII master), N:N network protocol (so far, only available in LX3VP series PLC). The communication protocol is set by D8126, the communication parameters are set by D8120, the detailed as below.

RS (user-defined Protocol) Instruction Description

• S: the head address of the register where the to be sent data stored in
• m: the length of the to be sent data (byte), 0 to 256.
• D: the head address of the register where the receive data stored in
• n: the length of the receive data(byte),0 to 256

Example

When X1 is ON, the receive data and the sand data is shown as below.

The RS (MODBUS mode) instruction automatically sets the M8123 once every time a transmit data is received and the acknowledge operation is received. Using this flag, it is possible to determine whether the RS instruction has been executed.

In actual programming, you need to do some preparation for serial communication and configuration, such as baud rate, check bit, timeout judgment condition, protocol etc. The same example, a relatively complete set of RS communication procedures are as follows.

RS (MODBUS Protocol) Instruction Description

The definitions of each operand in the RS (MODBUS mode) instruction are different from those of a standard RS instruction (user-defined protocol).

• S: Slave address (high byte), communication command (low byte, defined by MODBUS protocol);
• m: Start address of accessing slave;
• D: Data length, unit: word;
• n: Start address of data storage, the take up length of the subsequent address defined by D;

Program example

The PLC is set to MODBUS-RTU master mode, it reads data from address 100 of Slave 1, and read the data stored in D10.

6.14.2 RS2 instruction

Instruction description

This instruction is mainly used for serial data transfer instruction in BD board module.

RS2 is a transceiver instruction that automatically sends the data stored in the specific register to the serial port sequentially and stores the data received by serial port in the specific area. It is equivalent to directly access the communication buffer.

The RS2 instruction is used to configure the communication protocol according to the CPAVL instruction. For details, refer to the LX3V-2RS485-BD User's Manual, LX3V-ETH-BD User's Manual or the CPAVL Instruction Manual.

In LX3V-2RS485-BD module

• User-defined protocol

S: Starting address of transmitted data.

m: Length of transmitted data, the range is 0~256

D: Starting address for storage data.

n: Length of received data, the range is 0~256

n1: Serial port Number, 2 means using COM2, 3 means using COM3, 4 means using COM4, 5 means using COM5, 6 means using COM6; Program could write multiple RS2 instructions, but only one RS2 instruction could be triggered at the same time.

In this example, n1 is set K2, so the RS2 instruction is used in COM2. When X1 is triggered program will transfer data as below shows.

• MODBUS protocol

The definitions of each operand in the RS2 (MODBUS mode) instruction are different from those of a standard RS instruction (user-defined protocol).

S: Slave station address (high byte), communicational command (low byte, define by MODBUS protocol);

M: Register start address of call on slave station;

D: Data length will be read or write, units is word;

N: Memory units original address for read or write data, engross continuous address units, length decided by D;

n1: Serial port Number, 2 means using COM2, 3 means using COM3, 4 means using COM4, 5 means using COM5, 6 means using COM6; Program could write multiple RS2 instructions, but only one RS2 instruction could be triggered at the same time.

In this example, n1 is set K2, so the RS2 instruction is used in COM2. When X1 is triggered program will transfer data as below shows.

In LX3V-ETH-BD module

• MODBUS TCP protocol

S: The address of slave (high byte) and communication command (low byte, defined by MODBUS protocol);

m: The starting address number of the slave

D: The length of the data (read or writes), the unit is word. (The specific setting is shown in the following table)

n: The starting address of the storage unit for reading or writing data, occupying the subsequent address unit, and the length is determined by the D

n1: The connection number corresponding to the Ethernet port connection number (specific settings is shown as the following table)

Ethernet port 1		Connection number	Ethernet port 2		Connection number
	Connection 1	1000		Connection 1	1100
	Connection 2	1001		Connection 2	1101
	Connection 3	1002		Connection 3	1102
	Connection 4	1003		Connection 4	1103
	Connection 5	1004		Connection 5	1104
	Connection 6	1005		Connection 6	1105
	Connection 7	1006		Connection 7	1106
	Connection 8	1007		Connection 8	1107

In this example n1 is set as K1002, then RS2 is configured for Ethernet port 1, connection 3. When x1 is ON, the data is shown as below.

6.14.3 RSLIST instruction

Instruction description

Only LX3VP series and above plc (advanced series) support RSLIST instruction, and major version number and this version number of LX3VP series plc must be "25103" and "16001" and above edition, while major version number and this version number of LX3VPE series plc must be "25201" and "16001" and above edition.

This instruction is the one tabulating RS instruction, which replaces communication protocol by changing D8126 (communication protocol). Most of its functions are the same as the ones of RS instruction, but with simplified cumbersome engineering writing, in which, parameters of each transmission command are directly set by table.

S₁ is the starting device address controlled by table, with value range of D0~D7999; The addresses of starting device between S₁~S₄+4+n*6 couldnot be occupied by other instructions. (As far as possible, store data in power-down save (latched) (D200-D7999) to avoid data loss).

S₂ is the starting device address of table cache, with value range of D0~D7999; the addresses of cache starting device between S₂~S₂+12 couldnot be occupied by other instructions.

Note: any random data in the above operation-forbidden area will lead to communication anomalies.

m1 is the start address of communication flag, with value range of M0 ~ M3068; (m1~m1+2) couldnot be used by other instructions.

Other related settings are listed below:

Create new RSLIST table

Right click (Project Manager -> Project Property -> Extended Function -> RSLIST Table) to create or edit table, as shown below:

• Table setting interface as below
• Communication protocol: should be consistent with the configuration of communication protocol control address (D8126, etc.) (Modbus Master / RS user-defined protocol).
• Default error repeat count: use the replication number (retry times)of a single error when it is not 0; use the error replication number (retry times) set in header when it is 0; default 3 times when both are 0. The set replication number includes number of times for the first run, that is, repeat errors only for two times and then turn to the next when the set replication number is 2.
• Table initial address: should be consistent with in the corresponding RSLIST instruction.
• Address allocation: Table space could be automatically configured or selected as fixed length (4 + n * 6), where n is the number of communication commands.

✎Note: Number of table commands should be less than 255. And do address planning to avoid data confusion caused by repeatedly occupied addresses.

Modbus Protocol Configuration

• Ladder configuration

• Table configuration

Table start address is D300, which corresponds to the RSLIST instruction in ladder.

When M1 = ON, RSLIST instruction starts execution. When "YES" in "whether to enable command” is selected as instruction in the table ", number 1 and 3 instructions in execution table are executed cyclically; when “No” is selected, execution is controlled by “S₂+8”=D208. As shown in the above ladder, D208 = 2 is triggered every 500ms, that is, number 2 instruction in the table is executed every 500ms. (Read data of 20 addresses starting from station 100 and store the read data in D500-D519 separately).

• Communication command configuration

Slave station number: (limited between 0-255). Account 0 is used as broadcast and will not receive. See "Function Code List".

The data start address (D device) range in master station is (D0-D7999). Store relevant data in power-down save (D200-D7999) to avoid data loss. Store data start address in slave station.

Byte of data: (bit length in bits, word length in words), range 1 to 126 (word data), 1 to 2039 (bit data).

Error repeat time: 0 indicates that this error replication number (retry times) is the same as the one in table edit.

Default starting command:

Yes: execute cyclically when RSLIST is started;

No: execute only when +8 is in action.

RS User-defined Protocol

• Ladder configuration

• Table configuration

The table start address is D800, which corresponds to the RSLIST instruction in ladder.

When M2=ON, RSLIST instruction starts execution. When "YES" in "whether to enable command” is selected as instruction in the table ", number 2 instructions in execution table are executed cyclically; when “No” is selected, execution is controlled by“S₂+8”=D208. As shown in the above ladder, D708 = 1 is triggered every 500ms, that is, number 1 instruction in the table is executed every 500ms. (Send data of the 20 addresses starting from D1000 to device and store the returned data in the 20 addressed starting from D1020.)

• Communication command configuration

Starting address of delivery (D device) range is (D0-D7999). Store relevant data in power-down save (D200-D7999) to avoid data loss.

Sending length: the length here is in BYTE (range LX3VP: 0-528). No sending when the sent data length is 0.The receiving start address (D device) range is (D0-D7999). Store relevant data in power-down save (D200-D7999) to avoid data loss.

Receiving length: the length here is in BYTE (range LX3VP: 0-528). No receiving when the received data length is 0.

Error repeat count: 0 indicates that this error replication number (retry times)is the same as the one in table edit.

Default starting command:

Yes: execute cyclically when RSLIST is started;

No: execute only when +8 is in action;

6.14.4 CPAVL instruction (Ethernet port)

Instruction description

• S: The starting address of “D” device;
• D: The starting address of “M” device;
• M: Serial port Number, 0 means using COM0, 1 means using COM1, 2 means using COM2, 3 means using COM3, 4 means using COM4, 5 means using COM5, 6 means using COM6; Program could write multiple RS2 instructions, but only one RS2 instruction could be triggered at the same time.

✎Note: 

Only need one CPAVL instruction to configure multiple connections. The RS instruction needs to be used for the corresponding connection.

Address definition

• M device (Bit)

• D device (Word)

Program example

Use the Ethernet port 1, and the parameter table start from D300 and M300.

• The Ethernet parameter setting of LX3V-ETH-BD

• MODBUS protocol setting

6.14.5 CPAVL instruction (Serial port)

Instruction description

• S: The starting address of “D” device;
• D: The starting address of “M” device;
• M: Serial port Number, 0 means using COM0, 1 means using COM1, 2 means using COM2, 3 means using COM3, 4 means using COM4, 5 means using COM5, 6 means using COM6; Program could write multiple RS2 instructions, but only one RS2 instruction could be triggered at the same time.

Address definition

Setting the parameters of COM4 are in 20 consecutive addresses beginning of D0 and M0.

Program example

• MODBUS RTU Master

Users could set MODBUS RTU master communication by RS2 instruction, as above example shows. RS2 is a communication instruction, which could send data in the specified register area to the serial port and store receive data to specified register. Equivalent to the user program directly access the communication cache, with the help of the user program processing of the communication cache, to achieve the communication. RS instruction only is available in COM2 port, but RS2 instruction could be available in COM3/ COM4/ COM5/ COM6 ports.

• MODBUS ASCII Slave

When plc switches from stop to run state, PLC performs MODBUS RTU Slave communication; the function code and address mapping are consistent with COM2.

• User-defined

6.14.6 PRUN instruction

Instruction description

The instruction is used for coping the bit variables (the width unit is of octal) of the continuous addresses starting with S to the bit variable set starting with D in batch.

• S: The starting address of the bit variables to be copied, where the unit digit of the addresses must be 0, such as X10, M20;
• D: The starting address of the target bit variables, where the unit digit of the addresses must be 0, such as X10, M20;

Program example

Example 1

Example 2

6.14.7 ASCI instruction

Instruction description

This instruction reads n hexadecimal data characters from head source address (S) and converts them in to the equivalent ASCII code.

• S: The source address;
• D: The store address;
• n: The data length;

Program example

The M8161 flag determines the width mode of the target variable for calculation result storage. When M8161=OFF, it is 16bit mode, which means the higher byte and lower byte are saved respectively. When M8161=ON, it is 8bit mode, which means that only the lower byte is used to save result and the actual variable range length is longer.

• When M8161=OFF

When M8161=ON

Points to note

Instructions such as RS / HEX / ASCI / CCD share the M8161 mode flag, please pay attention on it when programming.

6.14.8 HEX instruction

Instruction description

This instruction reads n ASCII data bytes from head source address (S) and converts them in to the equivalent Hexadecimal character, and saved result in D.

• S: The variable address or constant to be converted. If it is a register variable, the conversion interval will has a width of a 32bit variable.
• D: The starting address for storing the ASCII code.
• n: The data length;

Program example

For example, the following data is starting from D100.

The M8161 flag determines the width mode of the target variable for calculation result storage. When M8161=OFF, it is 16bit mode, which means the higher byte and lower byte are saved respectively. When M8161=ON, it is 8bit mode, which means that only the lower byte is used to save result and the actual variable range length is longer.

• When M8161=OFF

• When M8161=ON

Points to note

• Instructions such as RS / HEX / ASCI / CCD share the M8161 mode flag, please pay attention on it when programming;
• S data area of the source data must be ASCII characters, or error occur when conversion;
• If the output data is in BCD format please do BCD-BIN conversion after HEX conversion, then users could get correct value;

6.14.9 CCD instruction

Instruction description

This instruction looks at a byte stack of data from head address (S) for n bytes and checks the vertical bit pattern for parity and sums the total data stack. These two pieces of data are then stored at the destination (D).

• S: The starting address of variables, which are to be checked and calculated;
• D: Respectively used for saving “SUM” result (D+1) is respectively used for saving “XOR” result;
• n: The bit number occupied by variables for checking

Program example

The M8161 flag determines the width mode of the target variable for calculation result storage. When M8161=OFF, it is 16bit mode, which means the higher byte and lower byte are saved respectively. When M8161=ON, it is 8bit mode, which means that only the lower byte is used to save result and the actual variable range length is longer.

The “SUM” is quite simply a summation of the total quantity of data in the data stack.

The "XOR" logical calculation means:

• The involved variables are converted to binary format.
• Then it counts the number of variables with bit0=1. If it is even, the calculation result of bit0 is 0. If it is odd, the calculation result of bit0 is 1.
• Then it counts the number of variables with bit1=1. If it is even, the calculation result of bit1 is 0; if it is odd, the calculation result of bit1 is 1.
• In the same way, calculation is implemented from bit2 to bit7. After that, the binary HEX value converted from binary is the “XOR” result (polarity value).

Note for use

• Instructions such as RS / HEX / ASCI / CCD share the M8161 mode flag, please pay attention on it when programming;

6.14.10 PID instruction

Instruction description

This instruction is for PID operation; it is used for control of close-loop system parameter. PID control is widely used in mechanical equipment, pneumatic equipment, constant pressure water supply, electronic equipment and so on.

• S₁: The predefined set value;
• S₂: The current value;
• S₃: The operation parameter, it takes the next 25 addresses, the value range is D0 ~ D7975, it is best to specify the retentive memory, for saving parameter when power OFF;
• D: The destination device, it is better to specify the non-retentive memory, otherwise users need to initialize it before executing instruction;

Program example

D9 is target value, D10 is current value, the unit for D9 and D10 must be the same.

D200~D224 are used for storing the set value and process value of PID operation. These values must be set item by item before executing PID operation.

D130 is used for storing the calculated value, it is used for controlling the implementation of the action.

• Self-tuning example

Error code

If an error occurs in the set value of the control parameters or in the PID operation, the operation error flag M8067 turns on and the following data is stored in D8067 according to the error details.

Note for use

The correct measured value must be read into the PID measured value (PV) before the PID operation is executed. In particular, pay attention to the conversion time when performing PID operation on the value of the analog input module.

PID instruction could be used multiple times and executed at the same time, but variable area of PID instruction couldnot overlap; it also could be used in step instruction, jump instruction, timer interruption, subroutine, but please delete S₃+9 cache unit before execute PID instruction.

The maximum error of sampling time TS is - (1 execution cycle+ l ms)~ +(1 execution cycle). If sampling time TS≤1 execution cycle OF PLC, then will have below PID operational error (K6740), and execute PID algorithm as TS = execution cycle, in that case, it is better to use constant scouldning mode or use the PID instruction in timer interrupt (16□□~18□□)