S

.SLC

The file extension used for text files exported from RSLogix 500, AI 500, or APS software. These files can be translated into .L5K files for use in the

Logix Designer

application.

S-curve

A velocity profile that provides for "controlled jerk" acceleration and deceleration. This type of profile is most often used when the stress on the mechanical system and load needs to be minimized. This profile, however, does not provide acceleration and deceleration times that are as fast as that of a trapezoidal profile. In addition, the speed of S-curve motion cannot be changed once the motion is started, except to zero.

safety add-on instruction

An instruction that has a class of safety and is defined as an add-on to the Logix defined instruction set; it is restricted to utilize only safety approved instructions and data types. The logic is currently restricted to RLL.

safety instruction signature

Consists of the ID, Date, and Time values corresponding to the creation of the Safety controller project. The date and time values correspond to when the signature was generated. The ID is a unique value calculated by the controller over the memory contents at the time the signature is generated. Also, note that when a Safety signature exists, there are editing restrictions similar to when Safety Locked. In this case, there are many things you cannot edit in the Safety portion of the application.

safety network number

A 48-bit number assigned to all Safety modules on the same Safety chassis/network. This number is used to prevent the acceptance of connection requests that have been misdirected by an intervening bridge module. Note that Safety modules connected to the same bridge module need not be on the same Safety network; they may have different Safety Network Numbers.

Choose from two formats:

Safety Partner Slot

The value you entered in the Slot field, plus 1. For example, if you entered a value of 1 in the Slot field, the Safety Partner Slot value will be equal to 2.

Safety controllers require two slots - 1 for the primary controller, and 1 for the Safety Partner. These slots must be side by side, with the partner always in the slot to the right of the primary controller.

This value applies to Safety controllers only.

safety task signature

The original signature that protects the entire safety controller application.

save

To upload (transfer) a program stored in memory from a controller to a personal computer, or to save a controller project to the project file on the computer’s hard disk.

scaling

The practice of using a multiplier to change a raw value into a number representative in user-defined units. This is used convert internal or sensor values into real world units such as degrees or meters.

scan time

The time required for the controller to execute the instructions in the program. The scan time may vary depending on the instructions and each instruction’s status during the scan.

A Logix controller provides two types of scan times. Each serves a different purpose.

SCANPort

A drive-specific communication protocol and associated physical implementation that was used by products prior to the invention of the DPI port and associated DPI protocol. The DPI specification is derived from and provides enhancements to the SCANPort protocol specification.

SCANPort is a non-CIP port that allows the connection of one of several SCANPort device types. A port expander is available that expands one port into four. All SCANPort compatible devices have at least 1 SCANPort port which may be used with a port expander, providing four free ports. These can be used by one or more communication modules for connection to ControlNet (1203-CN1, DeviceNet (1203-GU6/GK5), RIO (1203-GD1, etc., allowing network access to the drive.

A SCANPort can also be used by a 12-3-SSS (Anacanda), which allows a standalone PC to connect to the drive via an RS-232 DF1 serial connection.

schema line

A block separator that indicates the end of the previous block and the beginning of the next block. Any line whose first column is "Type" is interpreted as a schema line.

scope

The level at which tags and routines may be created. They can be created at the controller level (accessible to all routines), or the program level (accessible to only the routines within a single program).

sealed add-on instruction

An standard or safety add-on instruction that has a Signature, which means it has been sealed to prevent changes to the logic and definitions. (sometimes referred to as a “high integrity AOI”).

When an instruction is sealed, you can perform only the following actions:

searchable window

A window through which you can perform a search (for example, the Ladder Editor and Tag Editor/Data Monitor).

secondary control chassis

A control chassis that may or may not have a primary control chassis for a partner. A secondary control chassis may be either a disqualified secondary control chassis, or a synchronized secondary control chassis. A secondary chassis does not execute application programs.

secondary DNS server address

This configuration option allows a server to accept a text-based address and perform a database lookup to convert that address to an IP address that can be used by the network. If a message uses a host name address, it must be converted somehow to an IP address before it can be sent to the destination controller. When the controller has a DNS server address configured, then the DNS server is used to take the host name address and convert it to the IP address of the destination module and the message can be sent. The two fields are set to 0.0.0.0 by default.

Each octet of the IP address must be in the range of 0…255. The first octet cannot be 127 or greater than 223.

secondary readiness

The ability of a secondary control chassis to carry out the assigned functions in the event of a primary control chassis failure. Three states of secondary readiness are possible:

security authority identifier

A unique ID generated for each FactoryTalk Directory scope object to differentiate one directory from another when you install FactoryTalk Services Platform 2.50 or later.

selectable timed interrupt (STI)

A PLC-5/SLC term. (See periodic task.)

sequence

An

Equipment Sequence

is a control program that coordinates the execution of

Equipment Phase

programs.

sequence diagram routine

A sequence diagram routine is assembled from sequence elements in a Step >Transition > Step pattern where > is a link. The direction of the link is always from the bottom of one element to the top of another element. You can assemble sequences that are a series of steps, parallel series of steps, conditionally executed series of steps, and conditionally executed loops. The branching structures are inserted into this pattern but do not count as steps or transitions in the overall pattern. The Step >Transition > Step pattern must hold true for each simultaneous or selective path.

sequence ID

A user-supplied identifier that is recorded in every event record to enable the identification of events generated with a specific running of an equipment sequence.

sequence modes

In

Equipment Sequence

s, sequence modes specify whether transitions fire automatically or manually. When the sequence mode is

Automatic

, the transitions operate without interruption. In

Manual

mode, the order of execution of steps may be specified by the operator. Sequence mode is distinct from ownership.

sequence state

Shows the current state of the displayed

Equipment Sequence

. States are:

sequence step

Each step represents one use of an

Equipment Phase

to perform an action in the manufacturing sequence. A step has step tags that are input values which are loaded into the associated phase, and output values which are data loaded from the

Equipment Phase

.

Sequencing attribute

The

Sequencing

attribute is a tag attribute for

Equipment Phase

and

Equipment Sequence

sequencing parameters that defines an input or an output parameter as being necessary for (internal and external) sequencing.

sequencing input parameter

A program scope tag belonging to an

Equipment Sequence

program that provides processing data required by the

Equipment Sequence

or its associated phases, to make a product.

sequencing instructions

The set of Logix Designer application instructions that can be used in Logix programs to access and command

Equipment Sequence

s. The set of instructions is similar to

Equipment Phase

instructions.

sequencing object

An equipment sequence or an equipment phase.

sequencing output parameter

A program scope tag belonging to an

Equipment Sequence

program that records data produced by the sequence or its associated phases while making a product.

sequencing parameter

A program scoped tag with a

Usage

of Input or Output and the

Sequencing

attribute checked TRUE.

sequential function chart (SFC)

A sequential function chart (SFC) is a flowchart that controls your machine or process. An SFC uses steps and transitions to perform specific operations or actions.

SERCOS

Serial Real-time Communications System IEC 1491 (EN 61491). SERCOS is a trademark of the SERCOS interest group.

serial

The time-sequential transmission of, storage of, or logic operations on data, using the same facilities for successive parts.

serial access

A memory characteristic where all data is entered sequentially at a single input or retrieved sequentially from a single output.

servo axis

An axis that is directly commanded to move to a given position or at a given velocity.

servo drive

A drive that contains an embedded servo loop that controls some portion of the motor dynamics. Typical servo drives contain an embedded velocity servo loop to control the attached motor at a given speed.

servo loop

The closed loop algorithm that drives the controlled output such that the feedback follows the desired or command input.

servo output

The output from a servo loop that excites the target device in accordance with the servo loop algorithm.

servo update period

The period at which the position and/or velocity feedback is sampled and a new servo loop is closed to generate a new servo output.

set

Defines the status of bits (Booleans) and values (non-Booleans).

Set indicates that the bit is set to 1 (On), and a value is set to any non-zero number.

set point (SP)

The variable representing the commanded state or value of the process being controlled in a feedback control loop.

shutdown

The process in which the axis servo action is immediately disabled, the servo amplifier output is zeroed, and the appropriate drive enable output is deactivated. Furthermore, this action opens the OK contact associated with the servo module which can be used to open the E-stop string to the drive power supply. Shutdown is the most severe action to a fault. It is usually reserved for faults that could endanger the machine, or the operator, if power is not removed as quickly as possible.

simultaneous divergence

A simultaneous divergence is a branching structure that allows steps in two or more paths to run in parallel.

single-ended mode

An operating mode used by analog input modules where each channel uses one physical hardware channel.

Single-Slot Addressing

See 1-Slot Addressing.

sinking

The current flow between an I/O device and controller I/O circuit. Typically, a sinking device or circuit provides a path to the ground, low, or negative side of the power supply.

SINT

An atomic data type that stores an 8-bit signed integer value (-128 to +127).

slave axis

An axis that follows a master axis in an electronic gearing or position cam application.

slewing

An incremental motion of the motor shaft or machine table from one position to another, at maximum speed, without losing position control.

slot number

The number that indicates the physical location of the slot in the chassis where the controller resides. If you enter a slot number that is out of range for the specified chassis, you will receive an error message when you apply your changes. The slot number cannot be changed when online.

In ControlLogix, controllers occupy a numbered slot in the chassis and can be placed in any slot. It is also possible to place multiple controllers in the same chassis.

For SoftLogix controllers, the default value is 1. You also have the option to place modules in slot 0.

For CompactLogix, DriveLogix, and FlexLogix, since the controller always resides in slot 0 of the virtual backplane, this field is disabled, and slot number 0 is displayed.

For Safety controllers, valid values range from 0 to two less than the number of slots in the chassis (for example, in a 10-slot chassis, valid values will range from 0 to 8).

software

An executable programming package used to develop a controller project.

source key

User-generated, case-sensitive password that locks

Logix Designer

components from being viewed or modified by third parties.

source key name

Descriptive text that helps identify a source key. Where appropriate,

Logix Designer

software displays the source key name in place of the source key itself. This provides an additional layer of security for the source key.

source system

One of two coordinate systems used in a Kinematics transform and having special properties. When connected to a target system by means of a Kinematics transform, motion commanded at the source system’s inputs produces motion at both the source and target system’s outputs (if the physical axes are connected).

sourcing

The current flow between an I/O device and controller I/O circuit. Typically, a sourcing device or circuit provides a path to the source, high, or positive side of the power supply.

stack

A section of memory used to store information during subroutine execution. Information placed on the stack includes subroutine parameters as well as the location to resume execution when the subroutine is complete.

stack overflow

A condition that occurs when the stack (which may be fixed in size) has insufficient space available for a subroutine call.

standalone chassis

An ICP chassis, with its resident modules, that is not capable of, or not configured for, redundancy.

status

The condition of the circuit or system represented as logic 0 (Off) or logic 1 (On).

This term is also used to describe module status as follows:

status only

A fault action that causes no action to be taken other than setting appropriate status indicators. Any motion faults must be handled by the application program. In general, this setting should only be used in applications where the standard fault actions are not appropriate.

step function

A signal that has a zero value before a certain instant of time and a constant non-zero value immediately after that instant.

step-function response

The time variation of an output signal when a specified step function input signal or disturbance is applied.

step input tag

A step input tag is a system-generated tag that is linked to an input parameter of the step’s associated equipment phase. A step tag’s

Value

attribute is automatically copied before the phase is commanded to START or copied when the phase requests the data, depending on the configuration of the equipment phase.

step output tag

A step output tag is a system-generated tag that is linked to an output parameter of the step’s associated equipment phase. The phase’s output parameter’s value is copied to the step output tag’s

Value

attribute automatically when the phase becomes STOPPED, ABORTED, or COMPLETE or when the phase requests the data be copied, depending on the configuration of the equipment phase.

step response

The time required for the analog input signal to reach 95% of its expected final value (for inputs).

step states

When a step is not active, the step state is inactive. When a step is active, and attached to an equipment phase, the step state mirrors the state of the equipment phase. The step states are also represented by the color of the step:

Steps with a No Phase phase only have three displayed step states:

step tags

Equipment Sequence

step input tags and step output tags are automatically created when you assign an

Equipment Phase

to a step in an

Equipment Sequence

. The step tags hold input data that is loaded to the phase input parameters and output data that is read from the phase output parameters. This allows the

Equipment Phase

to be used by multiple steps within an

Equipment Sequence

.

sticktion

The level of force caused by static friction that must be overcome before an actuator can move freely. This level is often greater than the viscous friction level at low speeds. This causes an actuator to require less force to move than it does to initially break free.

stop command

A fault action that causes the axis to immediately start decelerating the command position to a stop, at the configured maximum deceleration rate, without disabling servo action or the servo modules drive enable output. This is the gentlest stopping mechanism in response to a fault. It is usually used for less severe faults since they are easier from which to recover.

String

A user-defined data type with two members. The first member is a DINT, which holds the number of characters in use. The second member is a SINT array of a configurable length, which holds the character data for the string.

structure

A data type composed of a sequence of members. A structure tag occupies a contiguous block of memory in the controller with each member in sequence in memory.

style

The form in which numeric values can be displayed. The following table provides you with information on the base and notation used for each style.

subnet mask

Subnet addressing is an extension of the IP address scheme that allows a site to use a single net ID for multiple physical networks. Routing outside of the site continues by dividing the IP address into a net ID and a host ID via the class. Inside a site, the subnet mask is used to redivide the IP address into a custom net ID portion and host ID portion. This field is set to 0.0.0.0 by default.

For example, use Network 2, a Class B network, and add another physical network. Selecting the following subnet mask adds two additional net ID bits, allowing for four physical networks:

11111111 11111111 11000000 00000000 = 255.255.192.0

Two bits of the Class B host ID have been used to extend the net ID. Each unique combination of bits in the part of the host ID where subnet mask bits are 1 specifies a different physical network. The new configuration is:

A second network with Hosts D and E has been added. Gateway G2 connects Network 2.1 with Network 2.2. Hosts D and E will use Gateway G2 to communicate with hosts not on Network 2.2. Hosts B and C will use Gateway G to communicate with hosts not on Network 2.1. When B is communicating with D, G (the configured Gateway for B) will route the data from B to D through G2.

subroutine

A routine that is called by another routine through the use of a JSR instruction. It must begin with a SBR instruction and contain at least one RET instruction.

subscript

See index.

synchronized secondary

A chassis that has a partner a primary control chassis, and whose state and data information is synchronized with the primary control chassis. A synchronized secondary is capable of taking control of application programs with minimal impact to the assigned functions.

synchronizing primary

A chassis that has a partner secondary control chassis, and is currently attempting to achieve synchronization. This synchronization could be triggered as a result of:

synchronizing secondary

A chassis that has a partner primary control chassis, and is currently attempting to achieve synchronization. In this state of readiness, a secondary control chassis cannot assume the primary state.

synchronous

The simultaneous action applied to two or more circuits, devices, or machines.

syntax

The rules governing the structure of a language.

system overhead time slice

The percentage of time the controller allocates to perform communication and housekeeping functions.

system overshoot

The maximum value of a system deviation between the control variable and the command.

system redundancy module

A module that provides high speed dedicated communications between a primary control chassis and a secondary control chassis.

The module's primary responsibility is to coordinate the configuration, state, and data between primary and secondary control systems. One system redundancy module resides in each chassis.