Collector Siemens S7

Updated on 15 Mar 2022
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The purpose of this article is to be a reference for the Siemens S7 collector part of the full Data Collection Module documentation.

Prerequisite

A Starter package (SiteManager + accounts) A Siemens S7 capable device.

Config main

The Config main (array of objects, mandatory) contain the following fields:

Function	Type	Importance	Description
ConfigName	string	mandatory	Unique name for this configuration file. Follows the rules for names.
ConfigDescription	string	optional	text describing this configuration.
CheckpointInterval	integer == 0 or >= 60	optional	The interval with which all data from the internal datasample cache is saved to disk. This more unstable (power) the SiteManager, the more often data should be saved. Saving it often, however will also cost performance and wear on the hard-disk/flash. A value of 0 means, never checkpoint, otherwise it means interval in seconds between saves. If not specified the value 15 * 60 (15 minutes) is used.
AlarmsSaved	integer >= 4	optional	The number of alarms saved in the store-and-forward database. If this values is not specified, it will default to 32.
WaitForNTP	boolean	optional	Synchronize DCM data collection with NTP time. If this parameter is true, all DCM collectors will not begin collecting data until NTP is enabled and configured and NTP has synchronized date/time. If not specified, the value is true.

Since the JSON format itself doesn't define a comment notation, DCM accepts a fieldname comment with any type of value in any section.

Example of comment

"Comment": "Example of a comment for use in any section.":

The Collectors (array of objects, mandatory) list elements contains the following fields:

Function	Type	Importance	Description
CollectorName	string	mandatory	Unique name (within this configuration file) of a device to collect data from. (This is the name used in the agent configuration). Follows the normal rules for names.
CollectorDescription	string	optional	Description of this collector. For your use, no system function.)
CollectorIPAddr	string	optional	Default IP address (or DNS name) for the device to be polled. The agent Target IP address will take precedence over this.
CollectorPortno	integer > 0 and < 65535	optional	Default port number for the device to be polled. The agent Target Port number will take precedence over this. If neither CollectorPortno , nor agent Target Port Number, is specified, the appropriate port will be used, depending on the Protocol parameter value.
Alias	string	optional	This is the CollectorName of another collector, from which all the parameters (except CollectorName, CollectorDescription, CollectorIPAddr and CollectorPortno ) are copied from. An alias cannot refer to another alias.
Protocol	string-enum	mandatory	The protocol used to collect data. Currently 3 possible values exists: "OPC-UA/TCP", "Modbus/TCP", "Http/GET" and "Simulator".
ConnectRetryMin	integer > 0	mandatory	Minimum number of seconds before trying to reestablish a connection to the device being sampled. An exponential backoff algorithm is used to retry connection establishment, starting after ConnectRetryMin and increasing to ConnectRetryMax.
ConnectRetryMax	integer > 0	mandatory	Maximum number of seconds before trying to reestablish a connection to the device being sampled.
S7Access	object	optional	Collection of parameters needed to access a given S7/TCP server.
SamplePoints	array of objects	mandatory	List of samples to be collected, possibly aggregated and stored in the Store'n'Forward database.

S7Access

The S7Access objects contain the following elements:

Function	Type	Importance	Description
S7Model	string-enum	mandatory	The PLC model/type. The supported values are "S7-200", "S7-300" and "S7-1200".
S7Rack	Integer >= 0 and <= 7	optional	The Rack number for this unit. If not present, the value 0 is used.
S7Slot	Integer >= 0 and <= 31	optional	The Slot number for this unit. If not present, the value 1 is used.
S7ConnectionType	string-enum	optional	The connection type used by this collector. The supported values are "PG", "OP" and "APP". If not present, the value "OP" is used.
S7Timeout	integer > 0,	optional	The default timeout (in millisecond) for all S7 requests. If not present, the value 3000 is used.
S7LocalTSAP	Integer >= 0 and <= 65536	optional	The local protocol TSAP value needed to access the S7 server. If not present, 256 is used.

Samplepoint items

The Samplepoints objects contain the following elements:

Function	Type	Importance	Description
SampleName	string	mandatory	Name of this sampled value (sometimes called a tagname). Follows the normal rules for names.
SampleDescription	string	optional	Is a text description of this sample value.
SampleUnit	string	optional	Is a description of the unit of measurement for this sample.
SampleGroup	string	optional	Designates (in some datasrvs) that all samplepoints in that group should be handled (displayed) together. The DCM system itself places no meaning on this group affiliation.
SamplesSaved	integer > 0	optional	is the number of values collected that is saved in the Store'n'Forward database even after the values have been sent to all dataservers. When 0 is specified, the value can be used in aggregators. but nothing is sent via dataservers to cloud system. If left unspecified, values are only saved in the Store'n'Forward database until they have been delivered to all dataservers.
OnlySaveOnChanged	bool	optional	Control if new sample values should only be saved to the Store’n’Forward database if the values have changed since last sample. If not set, it is false.
SampleDataType	string-enum	mandatory	The type of data collected. The possible values are: "bool" (1 bit), "sbyte" (8 bit signed), "byte" (8 bit unsigned), "int16" (16 bit signed), "uint16" (16 bit unsigned), "int32" (32 signed), "uint32" (32 bit unsigned), "int64" (64 bit signed), "uint64" (64 bit unsigned), "float" (32 bit), "double" (64 bit), "string" (variable text up to 24575 bytes. Includes terminating NUL), "data" (variable variable data up to 24575 bytes).
SampleMaxVDataSize	integer > 0 and <= 24575	optional	is the max size of variable data enforced for this sample. This is only relevant for SampleDataType "string" or "data". If not specified, the value is 1024.
SampleLowerLimit	integer/double	optional	The lower limit for the collected data. If the collected data value is less than SampleLowerLimit, it is evaluated in accordance to SampleLimitDiscard and SampleLimitAlarm.
SampleUpperLimit	integer/double	optional	The upper limit for the collected data. If the collected data value is more than SampleUpperLimit, it is evaluated in accordance to SampleLimitDiscard and SampleLimitAlarm.
SampleLimitDiscard	bool	maybe-optional	Controls if a sample limit violation results in the sample value being discarded. Mandatory if either SampleLowerLimit or SampleUpperLimit is present.
SampleLimitAlarm	bool	maybe-optional	Controls if a sample limit violation generates an alarm. Mandatory if either SampleLowerLimit or SampleUpperLimit is present.
S7Var	Object	maybe-optional	Description of how to address a specific datavalue from an S7 server. Mandatory if the protocol type is "S7/TCP".

S7Var

The S7Var object contains the following fields:

Function	Type	Importance	Description
S7PLCVar	String	mandatory	This is the absolute address of an S7 PLC variable using the S7 international syntax.
S7SampleInterval	integer >= 0	mandatory	The number of seconds between each sample of this S7 variable. If the interval is 0, only eventdriven polling is used.
S7Timeout	Integer > 0	optional	Timeout (in millisecs) for reading this S7 variable. If not present, the S7Timeout value from S7Access is used.

The S7 PLC variable absolute address syntax is as follows

AREA[DBNO][TYPE]BYTEOFFSET[.BITPOS].

BYTEOFFSET is the offset within the AREA, where this value starts. It is a decimal number between 0 and 16777215.
If the TYPE is "X" (or ""), an additional BITPOS is used to designate which bit within the BYTEOFFSET is addressed. BITPOS is a digit between 0 and 7.

Here AREA can one of the following strings:
• "I" or "E" for Digital input.
• "Q" or "A" for Digital output.
• "AI" or "AE" for Analog input.
• "AQ" or "AA" for Analog output.
• "M" for internal memory.
• "SM" for special memory. (only for S7-200).
• "DB" for data block.
• "DI" for indirect data block.
• "L" for local variables (corresponds to DB2 area).
• "V" for global variables (corresponds to DB1 area).
• "C" or "Z" for counters (for S7-200 this is the IEC Counter type).
• "T" for timers (for S7-200 this is the IEC Timer type).
while DBNO is only used if AREA is "DB" or "DI".
TYPE can be one of the following strings:
• "B" for byte (unsigned 8bit value)
• "C" for char (signed 8bit value)
• "W" for word (unsigned 16bit value)
• "WI" or "WINT" for word (signed 16bit value)
• "D" for doubleword (unsigned 32bit value)
• "DI" or "DINT" for double word (signed 32bit value)
• "R" for real (IEEE floating point 32bit value)
• "X" or "" for bit (1bit value)

Siemens Datatype	Secomea SampleDataType	General definition	S7Var definition
byte	sbyte	unsigned 8bit	B
char	byte	signed 8bit	C
word	uint16	unsigned 16bit	W
word	int16	signed 16bit	WI or WINT
doubleword	uint32	unsigned 32bit	D
double word	int32	signed 32bit	DI or DINT
real	float	IEEE floating point 32bit	R
bit	bool	1bit	X

{
     "CollectorDescription": "S71500 example",
     "CollectorName": "s7-1500",
     "ConnectRetryMax": 240,
     "ConnectRetryMin": 2,
     "Protocol": "S7/TCP",
     "S7Access": {
         "S7Model": "S7-1200",
         "S7Rack": 0,
         "S7Slot": 1
     },
     "SamplePoints": [
         {
             "SampleName": "DB1500Switch1",
             "SampleDescription": "DB1500DState0 S7",
             "SampleDataType": "bool",
             "SampleUnit": "On/Off",
             "SamplesSaved": 1000,
             "S7Var": {
                   "S7PLCVar": "DB1500X0.0",
                   "S7SampleInterval": 1
             }
         }
     ]
}

See complete Siemens S7 examples here:

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What's Next

Collector SiteManager Internal

Table of contents

Prerequisite
Config main
S7Access
Samplepoint items
S7Var