Siemens ET 200pro - Page 436

Analog electronic modules
15.9 Dynamic reference temperature for the 4 AI TC High Feature electronic module
ET 200pro distributed I/O system
436 Operating Instructions, 03/2013, A5E00335544-08
Requirements:
● Input address of the 4 AI TC High Feature electronic module: 120 (module address)
● Input address of the RTD module: 128 (channel address)
● Requirement bit for "WRREC" SFB: M 20.0
● Busy bit for "WRREC" SFB: M 20.1
● Memory for data transfer: MW 0 to MW 8
STL
Explanation
UN M 20.0
Check the requirement: New dynamic ref. temp.
UN M 20.1
Check whether WRREC is "Busy"
SPB END
Skip if no transfer is required
U M 20.1
Check whether WRREC is "Busy"
SPB WRT
// Create memory for data transfer
L B#16#1
Convert the temperature into hundredths of degrees (Pt 100 climatic)
T MB 0
L B#16#0
Convert the temperature into Celsius
T MB 1
L PEW 128
Read in the reference junction temperature of the RTD module
T MW 2
For channel 0 of the 4 AI TC High Feature
T MW 4
For channel 1 of the 4 AI TC High Feature
T MW 6
For channel 2 of the 4 AI TC High Feature
T MW 8
For channel 3 of the 4 AI TC High Feature
// Transfer the reference junction temperature to the 4 AI TC High Feature
WRT :CALL "WRREC", DB53
REQ :=M20.0
Requirement bit for data transfer
ID :=DW#16#80
Input address 128 of the 4 AI TC High Feature
INDEX :=2
Data record no. must be set to 2
LEN :=10
Length 10 bytes
DONE :=
BUSY :=M20.1
Busy bit of "WRREC" SFB
ERROR :=
STATUS :=MD24
RECORD :=P#M0.0 BYTE 10
Pointer on the memory for data transfer, length 10 bytes
U M 20.1
Check whether WRREC is "Busy"
SPB END
CLR
= M 20.0
Reset requirement for dynamic ref. temp.
END :NOP 0
This is just an example. The logic and memory allocation must be adapted to the structure of
the particular PLC program used.