Program instructions
7.3 Communication
S7-200 SMART
170 System Manual, 09/2015, A5E03822230-AC
Note
Compact S7-200 SMART CPU models CR40 and CR60 do not have a RTC (Real Time
Clock) or super cap
The READ_RTC and SET_RTC instructions can be used to set the year, date, and time
values in CPU models CR40 and CR60, but the values
will be lost on the next CPU power
-on cycle. On power-up, the date and time will initialize to January 1, 2000.
You can use the GET and PUT instructions for communication between S7-200 SMART
CPUs through the Ethernet connection:
Table 7- 1 GET and PUT instructions
The GET instruction initiates a communications operation on the
Ethernet port to gather data from a remote device, as defined in the
description table (TABLE).
The GET instruction can read up to 222 bytes of information from a
The PUT instruction initiates a communications operation on the
Ethernet port to write data to a remote device, as defined in the
description table (TABLE).
The PUT instruction can write up to 212 bytes of information to a
You can have any number of GET and PUT instructions in the program, but only a maximum
of 16 GET and PUT instructions can be activated at any one time. For example, you can
have eight GET and eight PUT instructions, or six GET and ten PUT instructions, active at
the same time in a given CPU.
When you execute a GET or PUT instruction, the CPU makes an Ethernet connection to the
remote IP address in the GET or PUT table. The CPU maintains a maximum of eight
connections at a time. Once a connection is established, that connection is maintained until
the CPU goes to STOP mode.
The CPU utilizes a single connection for all GET/PUT instructions that are directed to the
same IP address. For example, if there are three GET instructions enabled at the same time
when the remote IP address is 192.168.2.10, then the GET instructions execute sequentially
on one Ethernet connection to IP address 192.168.2.10.
If you try to create a ninth connection (a ninth IP address), the CPU searches through the
connections to find the connection that has been inactive for the longest period of time. The
CPU disconnects this connection and then creates a connection to the new IP address.
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