© Siemens, All rights reserved Ⓟ 2012
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SIMATIC
S7-1200
Update to the S7-1200 System Manual, edition 04/2012
Product Information
In spite of efforts to ensure the accuracy and clarity in the product documentation, some of the pages in the
S7-1200
Programmable Controller System Manual
contain information that has been identified as being incomplete, incorrect or
misleading.
New modules for the S7-1200
New modules expand the power of the S7-1200 CPU and provide the flexibility to meet your automation needs:
● New and improved CPUs:
– New CPU 1215C DC/DC/DC, CPU 1215C DC/DC/Relay, and CPU 1215C AC/DC/Relay offer 100 Kbytes of work
memory, dual Ethernet, and analog outputs.
– New and improved CPU 1211Cs, CPU 1212Cs, and CPU 1214Cs have faster processing time, the possibility of 4
PTOs (the CPU 1211C requires a signal board), increased retentive memory (10 Kbytes), and increased time-of-day
hold up time (20 days).
● New I/O signal module: SM 1231 AI 4 x 16-bit provides higher sample rate and increased number of bits.
● New battery board (BB 1297) offers long term backup of the real-time clock. The BB 1297 is pluggable in the signal
board slot of the S7-1200 CPU (firmware V3.0 and later versions).
Prerequisites
To use the new modules you must use STEP 7 V11 SP2 Update 3 or later (Basic or Professional) and you must download
the hardware support package (HSP) for new modules from the STEP 7 Options > Support Packages menu command.
Follow the instructions for adding modules to the hardware catalog for STEP 7 (TIA Portal) from the Siemens Service and
Support Site (http://support.automation.siemens.com).
S7-1200 behavior following a fatal error
When the S7-1200 CPU detects a fatal error, it enters a defective state and performs the following actions:
1. Turns on the error LED: When the CPU goes defective, it attempts to signal the condition by flashing the error LED.
Note: The defective state of the CPU, however, might prevent the CPU from flashing the error LED.
2. Performs a warm restart, which removes the user program, hardware configuration and resets all outputs to 0.
Note
A defective state is not a STOP state or non-fatal error state where the user program remains and restores outputs to
their substitute values.
Securing access to the S7-1200 CPU
As described in the Chapter 11, Web Server, section 11.1 "Enabling the Web server" in the S7-1200 Programmable
Controller System Manual, take care to avoid unauthorized access to the CPU from the Web server interface. In addition to
the security practices described in the topic "Enabling the Web server", also ensure that you isolate the CPU network behind
a firewall.
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Incorrect HSC configuration after CPU version change
The S7-1200 CPU V3.0 does not require a high-speed counter for correct PTO operation. However, previous firmware
versions of the S7-1200 CPU (V1.0 or V2.x) do require an associated high-speed counter. It is possible to encounter compile
errors when exchanging CPUs between V3.0 and V1.0 or V2.x. The following are specific scenarios that exhibit this
behavior.
Scenario: PTO and motion V1.0 or V2.x to V3.0
When you have an S7-1200 CPU V1.0 or V2.x with enabled PTOs and select to exchange this CPU with a CPU that
supports V3.0, compile errors result from improperly configured high-speed counters due to differences in the operation of
PTO.
After the exchange, the resulting compile error appears as follows:
Workaround
To eliminate the compile error, follow these steps:
1. Double-click on the error in the compile output listing. The properties of the high-speed counter are displayed:
2. Select the "Type of counting" field and select one of the available options ("Frequency" or "Count"). The entry is no
longer red.
3. Next, select the "General" section of the properties, as shown below:
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4. Deselect the "Enable this high-speed counter" checkbox. The high-speed counter is no longer needed for correct PTO
operation.
5. Recompile your project and verify that the compile succeeds.
Scenario: PTO V3.0 to V1.0 or V2.x
When you have an S7-1200 CPU V3.0 with enabled PTO and select to exchange this CPU with a CPU that only supports
older firmware version (V1.0 or V2.x), compile errors result from improperly configured high-speed counters due to
differences in the operation of PTO.
The resulting compile error appears as follows:
Workaround
To eliminate the compile error, follow these steps:
1. Double-click on the error in the compile output listing. The properties of the pulse output appear as follows.
2. Set the "Pulse generator" to "PWM", select another field, then select the "Pulse generator" field and change it back to
"PTO". This causes the associated high-speed counter to be configured correctly if it is not already in use.
3. Recompile your project and verify that the compile succeeds.
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Note
If you configured an associated high-speed counter for "counting" or "frequency", a compile error is still shown. You need
to make changes to your program in order to use PTO.
Scenario: Enabled motion control V3.0 to V1.0 or V2.x
When you have an S7-1200 CPU V3.0 using motion functionality and select to exchange this CPU with a CPU that only
supports older firmware version (V1.0 or V2.x), compile errors result from improperly configured high-speed counters and
motion control support.
Motion Support
● V1.0 PLC V1.0 Motion
● V2.x PLC V1.0, 2.0 Motion
● V3.0 PLC V1.0, 2.0, 3.0 Motion
The resulting compile error appears as follows:
Workaround
To eliminate the compile error, follow these steps:
1. Select the "Properties" tab for the PLC
2. Select the "high-speed counter" for the Axis configured and enable it.
– HSC1 must be associated with Axis 1
– HSC2 must be associated with Axis 2
Note
V1.0 and V2.x only support two (2) axes of motion. V3.0 supports four (4) axes of motion. When converting from V3
to V1.0 or V2.x, you must delete axes not assigned to PTO1 or PTO2 from the project prior to download.
3. Expand the "high-speed counter" and select "Axis" as the "Type of counting". Do this for each axis.
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4. Save and recompile your project. If you have used V3.0 motion elements in the program, a compile error occurs.
5. Open the "Instruction Tree" and select the appropriate version for the PLC being used. Appropriate versions are
indicated when the motion instructions are selectable.
6. You must replace all blocks with the version-appropriate motion instructions.
7. Recompile and download the project.
Incomplete password configuration
If you select a protection level other than "No Protection" but do not specify a password or a matching password, then a
compile error results. However, if you select compile again, the compile error is cleared and you are allowed to download the
project. The level of protection that was selected is put in place, but you cannot access the protected functions of the PLC
because a valid password cannot be entered.
Workaround
You must clear the PLC by using an empty transfer card. For more information about how to create and use an empty
transfer card, refer to Chapter 4, PLC concepts, section 4.5.3 "Transfer card" of the S7-1200 Programmable Controller
System Manual.
String or array compile error
If you cannot successfully compile program blocks containing strings or arrays which successfully compiled in a previous
version of STEP 7, an error results.
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Workaround
Right-click "Program blocks" in the project tree and select "Compile" and "Software (rebuild all blocks)".
Modifying Real value tags from the Web server
WARNING
Using the Variable Status Web page to modify Real data type tags with non-floating point values (for example,
hexadecimal values) can produce unintended value modifications.
Modifying PLC data with unintended values can cause unexpected machine or process operation which could result in
death, serious injury or property damage.
When you modify values for a PLC tag or data block tag from the Variable Status standard Web page for a Real data type,
be sure you enter floating point values that include a decimal point on the Variable Status Web page.
Example
For example, consider a project with the following tags:
● PLC tag table: "Tag_1", data type Real
● Data block: "Data_block_1".db_tag, data type Real
When you enter these tags in the Address field of the Variable Status Web page, use floating point values in the Modify
Value field, such as "10.0".
Floating-point values have different internal representations than integer values or hexadecimal values. If you configure tags
in STEP 7 to use Real data types, you must modify those tags as Real values in your STEP 7 user program, on the Variable
Status Web page, and any other usage. Do not try to write hexadecimal representations into a Real tag from the Variable
Status Web page. The Web server converts the hexadecimal value to a Real value, which is NOT the same internal bit
representation as the hexadecimal value.
Note
If you modify values for an absolute memory address such as MD100 or DB1.DBD1, using non-floating point values on the
Variable Status Web page does not produce unintended results. Because there is no associated data type, the Web server
makes no conversion based on the STEP 7 data type and modifies the value exactly as you enter it.
Unintended results can occur only when you use non-floating point values for PLC tags or data block tags of data type Real.
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Update to the S7-1200 System Manual, edition 04/2012
A5E03929122-AB, 07/2012
