RAM registers, such as D, BW, MW, SW, T, C, have fast access speed.
Keep register: R register. In V200 and some OIS PLUS models, the R register is stored in EEPROM, which can hold data for more than 200 years, but the write operation limit is about 10 million times, and the access speed is slow (in milliseconds). In OIS10/40 PLUS, the R register is implemented by battery backed RAM, with the same speed as RAM.
Programming advice: Be cautious when using the R register as the target operand in scenarios that require frequent writing and are sensitive to speed.
2.2 Overview of Main Instruction Categories and Functions
I/O instructions: including basic logic components such as normally open/normally closed contacts, output coils, positive/negative jump detection, etc.
Data transfer instructions: such as MOV (word/double word transfer), data block transfer, data exchange, multiplexing/demultiplexing, etc., used for data transfer and reassembly between registers.
Arithmetic operation instructions: support addition, subtraction, multiplication, division of words, double words, floating-point numbers, as well as complex operations such as carry addition/subtraction, increment/decrement, logarithm, exponent, square root, etc.
Comparison instruction: Provides a complete set of comparison functions such as greater than, equal to, less than, etc., supporting signed, unsigned, doubleword, and floating-point formats respectively.
Logic and shift instructions: including logic and/or XOR, bit left and right shift, loop shift, shift register, etc., suitable for bit processing and sequence operations.
Conversion instructions: Implement hexadecimal and ASCII code conversion, absolute value, complement, seven segment decoding, BCD and binary conversion, integer and floating-point number conversion, etc.
Timer and Counter: Provides on delay, off delay, single trigger timer, as well as regular and reversible counters.
Program control instructions: subroutine call/return, loop (FOR-NEXT), main control (MCS/MCR), jump (JCS/JCR), interrupt enable/disable, etc.
Functional instructions: moving average, digital filtering, PID control (two algorithms provided), upper and lower limit amplitudes, maximum/minimum/average value lookup, function generator, etc.
Special instructions: including device/register reset, carry flag operation, encoding/decoding, bit counting, trigger, direct I/O, calendar setting and operation, etc.
2.3 Examples and Techniques of Key Instruction Applications
Data block operation: TMOV (table transfer) and TNOT (table fetch reverse transfer) instructions support source and destination region overlap and are suitable for sliding window processing of data buffers.
PID Control: The manual provides two types of PID commands. PID1 adopts pre differentiation real-time algorithm, with flexible parameter configuration; PID4 has a more organized structure, including dead zone settings and positive and negative action selection. Ensure that the PID instruction is executed once per scan cycle during use.
Step sequence control: By using the STIZ (initialization), STIN (step input), and STOT (step output) instruction sets, sequential flow control programs can be efficiently written, supporting parallel sequences, merging, and conditional branching.
Direct I/O: The Direct I/O instruction can immediately update all physical input/output states of a specified slot, suitable for interrupt programs or critical control segments that require extremely high real-time performance.
Shift register: used to implement first in first out queue or bit sequence processing. Note that the shift input signal should use jump contacts to prevent shifting every scanning cycle.

Chapter 3: Practical Guide - Programming and System Debugging Suggestions
3.1 Programming Environment and Property Settings
V200 is programmed using Windows based software. When placing instructions, a "Properties" docking window will appear on the right side of the software, allowing users to dynamically adjust the data type (signed, unsigned, floating-point) and data length (word, doubleword) of the instruction. This greatly increases the flexibility of programming.
3.2 Error Handling and Flag Bit
Instruction Error Flag (ERF): Typically the system flag S0034. Set when operations such as zero division or data format errors occur. The user program can reset it through the RST S0034 instruction.
Carry flag (CF): S0. Used for determining the results of carry operations and shift/rotate operations, which can be explicitly controlled through SETC and RSTC instructions.
Watchdog Timer: The WDR instruction can be used to extend the scanning time monitoring cycle, preventing watchdog timeout reset due to program complexity.
3.3 Data Recording and USB Functionality
Some models support USB data recording and uploading function (LD-UPLD). This command can generate a CSV file of the historical records of a specified time period and a specified data group, and save it to a USB flash drive. Users need to configure parameters such as start/end time, group number, and file name, and monitor task execution through status registers.