Special Functions (Via SBs & SIs) List

Click on the function name to view a Help topic containing specific instructions on how to implement the function.

Special Functions: without Ladder elements

U90Ladder contains special functions that are not represented by Ladder Elements. You can perform these functions by storing values into the System Integers listed here.

To implement a special function:

Store the parameters of the function in the relevant SI function operands.
Store the command number into SI 140.

Note that the command number must be stored into SI 140 after the parameters are stored into the operands.

SI	Description
140	Function Number
141	Function Operand #1
142	Function Operand #2
143	Function Operand #3
144	Function Operand #4
145	Function Operand #5
146	Function Operand #6
146	Function Operand #7

The example below shows the function A*B/C, which enables the PLC to multiply 2 operand values & divide the product by a third operand.

Function # (SI 140)	Description
100	Multiply A x B, Divide by C

Note that when you run Test (Debug) Mode, the current value in SI 140 will not be displayed.

The function stores the result in SI 144.

Functions activated by SI 140

Function Name	Description	Parameters	Execute Function, Store into SI140
A*B/C	Enables PLC to multiply 2 operand values & divide the product by a third operand.	SI 141 Operand A (multiplicand). SI 142 Operand B (multiplicand), SI 143 Operand C (divisor).	100
Change COM Port Parameters	Enables you to change the serial communication port default settings for M91 controllers. M90 models do not support this function.	SI 141 Baudrate SI 142 Data bits SI 143= Parity e SI 144 Hardware flow control SI 145 = Timeout 10ms units SI 146 = Stop bits SB 141 indicates whether the COM port has been successfully initialized with the new parameters successfully: 1 = success, 0 =fail	SI 140: 310
Communication Utility	Enables PLC to receive data from external devices, such as bar-code readers, via an RS232 port.	SI 141 STX SI 142 ETX SI 143 ETX Length or Silent SI 144 Maximum Length SI 145 Start Address: Receive Buffer SI 60 # of Bytes currently in Receive Buffer SI 61 # of Bytes in Receive Buffer when SB 60=1 SI 146 Copy Data: Format SB 60 Data Successfully Received	300 Additional Functions: Set SB 61 to Copy Data in Receive Buffer to Vector Set SB 62 to Clear Receive Buffer, Clear SI 60, Clear SI 61,& Reset SB 60
Copy Vector	Sets a vector, copies source values, then writes those values into a corresponding target vector.	SI 141 Source Vector SI 142 Vector Length SI 143 Target Vector	Copy MIs to MIs: 20 Copy MIs to DBs: 21 Copy DBs to MIs: 22 Copy DB to DB: 23
Copy vector of MBs	Sets an MB vector, copies source values, then writes those values into a corresponding target MB vector.	SI 141 Source MB Vector SI 142 Target Vector SI 143 Vector Length	24
Fill Vector	Copies a source value, then write that value into every operand within the target vector.	SI 141 Start of Target vector, SI 142 Length of Target vector, SI 143 Fill Value; register whose value will be written into each register within the target vector	Fill MI vector: 30 Fill DB vector: 31 Fill MB vector: 36
Set bit in MI vector	Sets a bit within an MI vector	SI 141 Start of MI vector, SI 142 Location of bit to be set within vector (offset)	37
Reset bit in MI vector	Resets a bit within an MI vector	SI 141 Start of MI vector, SI 142 Location of bit to be reset within vector (offset)	38
Test bit in MI Vector	Selects a bit within a vector of registers, and stores its status in an MB.	SI 141 Start of Target vector, SI 142 Location of bit to be set within vector (offset), SI 143 Target Bit, determines the address of the MB, where the value of the selected bit will be stored.	39
Find Mean, Maximum, and Minimum Values	Finds within vector: Mean, Minimum, & Maximum.	SI 141 Start of vector, SI 142 Length of vector	Find in MI vector: 40 Find in DB vector: 41
GSM PIN Code via MI	Uses an MI vector to supply a GSM modem PIN code	SI 141 Start of vector	410
Interrupt	Causes program to stop immediately without regard to program scan	See Interrupt for details	500
Loadcell	M91 PLCs support Loadcell via I/O Expansion modules IO-LCxx. Check the Loadcell topic for details and a commands list.
Load Indirect	Takes value contained in a source operand and loads that value into a target operand using indirect addressing	SI 141 Data source SI 142 Load target	Load MI to MI: 10 Load SI to MI: 11 Load MI to SI: 12 Load SI to SI: 13
Load Timer Preset/Current Value	Load a preset or current timer value into another operand	SI 141 to select the timer; 0-63	Load Timer Preset: 202 Load Timer Current: 203
MODBUS	Enables MODBUS Master/Slave communications	See MODBUS for details	Configure: 600, enable PC applications access (see MODBUS topic) Configure: 600 Read Coils: 601 Force Coil: 602 Force Coils: 603 Read Output Registers: 604 Preset Register: 605 Preset Registers:606 Read Input Registers: 609 Read Inputs: 611 Loopback Test: 612
SMS Phone Number: via MI Pointer	Uses an MI vector to supply a phone number in the SMS phone book	SI 141 Start address of the MI vector containing the phone number	Store 400 into SI 140
Store Timer's Preset/Current Value	Store a value into a timer to change the preset or current timer value.	SI 141 to select the timer; 0-63, SI 142 to determine the timer value, SI 143 to select the timer's resolution	Store Timer Preset: 200 Store Timer Current: 201
Square Root	Finds the square root of a number	SI 141 Store the number	Store 110 into SI 140
Temperature	Convert C° to F°	SI 141 Data Source: C° value SI 142 Result: F° value Degree value representation: 500 means 50.0	130
Temperature	Convert F° to C°	SI 141 Data Source:F° value SI 142 Result: C° value Degree value representation: 500 means 50.0	131

Functions activated by SBs

Function Name	Description	Parameters	Activating SB-SI
PID auto-tune (M91)	M91 controllers may be easily tuned via SBs. Each PID loop is linked to two SBs, one to activate auto-tune, and one that signals when the process is complete.	auto-tune parameters are taken from the PID function	SB101 Start auto-tune - Loop 1 SB102 Start auto-tune - Loop 2 s SB103 Start auto-tune - Loop 3 SB104 Start auto-tune - Loop 4 SB109 Select PID method (OFF by default) Turn ON to perform auto-tune
Convert MB to MI, MI to MB	Converts 16 bits or more into a integer value, or an integer value into 16 bits	SI 170 Address of MI containing integer value SI 171 Start address of MB array (vector) SI 172 Amount of MBs	Set SB 170 to activate MB to MI Set SB 171 to activate MI to MB
Copy MI to Output vector, Input vector to MI	Copy a vector of Inputs (I) to a register. Copy a register value to a vector of Outputs (O)	SI 170 Address of MI containing integer value SI 171 Start address of bit array (vector) SI 172 Amount of bits	Set SB 172 to activate I to MI Set SB 173 to activate MI to O
Database	The M90/91 has a special memory area containing integers that are function as a database.	Within the database, you can access and use integers 0 through 1023 via SI 40 and SI 41. See Using the Database for details.
Delete SMS messages	Delete SMS messages from a SIM card	SI 187, Number of SMS messages to be deleted	Set SB 193 to delete messages (default 20 messages)
Immediate: Read Inputs & HSC, Set/Reset Outputs	Perform immediate actions, without regard to the program scan.	Model-dependent; see Immediate: Read Inputs & HSC, Set/Reset Outputs for details.
Long Integer Functions	Uses adjacent MIs in performing calculations and storing results. Not supported byM90.		Set SB 82 to treat 2 registers as 'long integer'
Linearization	Convert analog values from I/Os into decimal or other integer values	SI 80 - 85: (x,y) variable ranges.	Set SB 80 to activate the Linearization function.
Shift Register	Load SI 87 with a value, use SBs to shift register bits left/right	SI 87 Contains the number to be shifted SI 88 contains the number of bits to be shifted (Default is 1 bit)	Set SB 87 to shift left Set SB 88 to shift right