User manual

Publication LOGIX-AP010B-EN-P - May 2010 99
Additional RSLogix 5000 Features Chapter 4
RSLogix 5000 software also allows the programmer to perform the following
conversions on string type variables.
• DINT to String (DTOS) – converts a numeric value to its ASCII
equivalent.
• String to Dint (STOD) – converts an ASCII representation to its
equivalent integer value.
• Real to String (RTOS) – converts a real value to its ASCII equivalent.
• String to Real (STOR) – converts an ASCII representation to its
equivalent real value.
• Upper – converts all the characters in a string to uppercase.
• Lower – converts all the characters in a string to lowercase.
RSLogix 5000 software also provides an instruction called Swap Byte (SWPB)
that rearranges the bytes order in a source and places the result in a
destination. This instruction cannot be executed on string type variables but
on double integers by using the ASCII display format to rearrange characters.
Coordinated System Time
(CST)
All S5 controllers, except S5-90U, have a system clock that set and read the
current date and time.
RSLogix 5000 software provides the GetSystemValue (GSV) and
SetSystemValue (SSV) instructions to access system status data, including date
and time. It does this by accessing the data assigned to objects. The two
date/time related objects are Coordinated System Time Object and
WallClockTime.
Coordinated System Time (CST) Object
The CST is a 64 bit, free-running timer with microsecond granularity on a
ControlLogix backplane. A time master, for example, a ControlLogix
controller or 1756-SYNCH module generates the timer and sets it on the
backplane. All other modules in the chassis have read-only access to the CST
and adjust their time reference based on the backplane time reference. CST
serves as a relative time reference.
WallClockTime
By setting parameters, this object keeps the current UTC time internally while
allowing access to other time zones and adjustment for daylight-savings time.