Whether you are adding a Gocator to an older production line or creating a new inspection station, it is important to make sure that your Siemens PLC selection will support the Gocator based system that you are designing.
First, a definition of Gocator SYSTEM.
A Gocator SYSTEM can be a singular standalone sensor or several sensors that are buddied together in any configuration (i.e. wide, reverse, opposite, grid, ring, etc.). In TIA Portal, a Gocator system is equivalent to an IO subsystem.
Second, a definition of I/O ADDRESS AREA as it relates to the Process Image
The process image includes code, text, and data segments necessary for the proper execution of a Siemens PLC program. The I/O Address Area is where the data to and from the sensor is stored as Profinet IO object modules or Hardware Submodules. Each Gocator system consumes the following:
Input Addresses: 961 bytes
Output Addresses: 272 bytes
The addresses must consist of 2 "blocks" of memory for the inputs and 3 "blocks" of memory for the outputs. The 3 input memory blocks are for the Hardware Submodules we call State module, Stamp module, and Measurements module. The State module consumes 116 Input Address bytes, and those 116 bytes must be consecutive in the data segment. Same goes for the other 2 Input blocks and the 2 output blocks. The current sizes of the 5 modules are:
Control (O) - 256 bytes
Runtime Variables (O) - 16 bytes
State (I) - 116 bytes
Stamp (I) - 45 bytes
Measurements (I) - 800 bytes
Finally, specify which PLC can support your proposed new sensor system(s).
With the memory requirements in mind, the 1200 and 1500 series Siemens PLCs each have a limitation of available memory called IO Address Area per Integrated IO Subsystem. For example, the CPU 1211C has a Process Image - Available Inputs of 1kbyte as shown below:
That means that only 1 sensor system can be supported by this model.
In the 1500 series, the data sheets look a little different, and the available memory is listed by subsystem.
Here the memory per Gocator sensor system is listed under "per integrated IO subsystem". While the additional memory per system is not needed, the total IO Address Area has increased to 32kbyte for both inputs and outputs which indicates that up to 33 sensor system could be saved in the process image. In reality, some of the process image inputs and outputs will also be consumed by the ladder logic, digital inputs and outputs, analog inputs and outputs, and more.
When specifying a PLC model, you should consider your program requirements as well as the "per-system" memory requirements. With that in mind, below is a chart of the available memory in each system that the Gocator could potentially consume a portion of. Only the critical memory location is noted, and the actual Siemens data sheets should be referenced during final selection.
PLC Model |
1211C |
1212C |
1214C |
1215C |
1217C |
1511-1 PN |
1513-1 PN |
1515-2 PN |
1516-3 PN/DP |
1517-3 PN/DP |
1518-4 PN/DP |
IO Address Area |
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|
|
|
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|
|
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|
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Inputs |
1 KB |
1 KB |
1 KB |
1 KB |
1 KB |
32 KB |
32 KB |
32 KB |
32 KB |
32 KB |
32 KB |
Outputs |
1 KB |
1 KB |
1 KB |
1 KB |
1 KB |
32 KB |
32 KB |
32 KB |
32 KB |
32 KB |
32 KB |
per integrated IO subsystem |
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Inputs |
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|
8 KB |
8 KB |
8 KB |
8 KB |
32 KB (X1) / 8 KB (X2 or 3) |
32 KB (X1) / 8 KB (X2 or 3) |
Outputs |
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|
|
|
|
8 KB |
8 KB |
8 KB |
8 KB |
32 KB (X1) / 8 KB (X2 or 3) |
32 KB (X1) / 8 KB (X2 or 3) |
Max # of Sensor Systems |
1 |
1 |
1 |
1 |
1 |
<32 |
<32 |
<32 |
<32 |
<32 |
<32 |
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