Topic: DMD0482
REST API
Ethernet-equipped BRX CPUs contain an HTTP-based RESTful API (REpresentational State Transfer, Application Programming Interface) that will return the contents of PLC memory locations in JSON formatted records. The REST API is accessed by a web browser using a URL with the appropriate parameters.
Can read any Bit location: will return 0 for OFF or 1 for ON. Can also read a block of up to 128 contiguous BITs.
Can read any numeric location: the value will be either signed decimal or floating point (real) depending on the data type of the element being read. Can also read a block of up to 128 contiguous numeric locations.
Can read any system-defined String or user-defined String.
Can read any system-defined or user-defined Structure with options to control how many of the structure fields will be in the returned data.
Can read any individual field from any system-defined or user-defined Structure.
Reading a single element from the PLC:
Format:
/data/json?MyName = <PLC Element>
Example:
<PLC IP Address>/data/json?MyDeeEssTeeZero=DST0
Response JSON record is an object containing the element's data value.
{
"MyDeeEssTeeZero":14437656
}
Reading multiple elements from the PLC:
Format:
/data/json?1stName = <1st Element>&2ndName = <2nd Element>&3rdName = <3rd Element>...
Example:
<PLC IP Address>/data/json?MyDeeEssTeeZero=DST0&MyYTen=Y10&MyStringFour=SS4
Response JSON record are objects containing the specified elements' data values.
{
"MyDeeZero":14437656,
"MyYTen":0,
"MyStringFour":"My Dog Has Fleas"
}
Reading a block of contiguous elements ( ,<count value> ) from the PLC (maximum of 128 consecutive elements):
Format:
/data/json?MyName = <PLC Element>,count
Example:
<PLC IP Address>/data/json?FirstTenDs=DST0,10&SomeExs=x10,16&FourStrings=SS4,4
Response JSON record is an array containing the specified number of consecutive elements' data values.
{
"FirstTenDs":[22911329,50,13,8593,46,0,32768,0,0,0],
"SomeExs":[0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,1],
"FourStrings":["My Dog Has Fleas","Your Dog Has Fleas","So Does His","Hers Does Too"]
}
Reading a structure from the PLC: Short list of fields ( S )
Format:
/data/json?MyStruct= <PLC structure>,S
Example:
<PLC IP Address>/data/json?MyMain=$Main,S&MyTimer=T0
Response JSON record is an object containing the most commonly used structure field names and their current data values.
{
"MyMain":{"RanThisScan":1,"Done":0,"TimeSlice":65535,"S0_15":0,"S16_31":0,"S32_47":0,"S48_63":0,"S64_79":0,"S80_95":0,"S96_111":0,"S112_127":0},
"MyTimer":{"Acc":0,"Done":0}
}
Reading a structure from the PLC: Long list of fields ( L )
Format:
/data/json?MyStruct= <PLC structure>,L
Example:
<PLC IP Address>/data/json?MyMain=$Main.L&MyTimer=T0,L
Response JSON record is an object containing the most of the structure field names and their current data values.
{
"MyMain":{"RanThisScan":1,"Done":0,"FirstRun":0,"TimeSlice":65535,"ScanCounter":37579023,"RunCounter":0,"S0_15":0,"S16_31":0,"S32_47":0,"S48_63":0,"S64_79":0,"S80_95":0,"S96_111":0,"S112_127":0},
"MyTimer":{"Acc":0,"Done":0,"Zero":1,"Timing":0,"Reset":1,"TT":0,"EN":0,"DN":0}
}
Reading a structure from the PLC: list All fields ( A )
Format:
/data/json?MyStruct= <PLC structure>,A
Example:
<PLC IP Address>/data/json?MyMain=$Main,A&MyTimer=T0,A
Response JSON record is an object containing all of the structure field names and their current data values.
{
"MyMain":{"Running":1,"RanThisScan":1,"Done":0,"FirstScan":0,"FirstRun":0,"DoneThisScan":0,"InstrSuspend":0,"DebugSuspend":0,"TimeSlice":65535,"ScanCounter":41210774,"RunCounter":0,
"S0_15":0,"S16_31":0,"S32_47":0,"S48_63":0,"S64_79":0,"S80_95":0,"S96_111":0,"S112_127":0,"S0":0,"S1":0,"S2":0,"S3":0,"S4":0,"S5":0,"S6":0,"S7":0,"S8":0,"S9":0,
"S10":0,"S11":0,"S12":0,"S13":0,"S14":0,"S15":0,"S16":0,"S17":0,"S18":0,"S19":0,"S20":0,"S21":0,"S22":0,"S23":0,"S24":0,"S25":0,"S26":0,"S27":0,"S28":0,"S29":0,"S30":0,
"S31":0,"S32":0,"S33":0,"S34":0,"S35":0,"S36":0,"S37":0,"S38":0,"S39":0,"S40":0,"S41":0,"S42":0,"S43":0,"S44":0,"S45":0,"S46":0,"S47":0,"S48":0,"S49":0,"S50":0,"S51":0,
"S52":0,"S53":0,"S54":0,"S55":0,"S56":0,"S57":0,"S58":0,"S59":0,"S60":0,"S61":0,"S62":0,"S63":0,"S64":0,"S65":0,"S66":0,"S67":0,"S68":0,"S69":0,"S70":0,"S71":0,"S72":0,
"S73":0,"S74":0,"S75":0,"S76":0,"S77":0,"S78":0,"S79":0,"S80":0,"S81":0,"S82":0,"S83":0,"S84":0,"S85":0,"S86":0,"S87":0,"S88":0,"S89":0,"S90":0,"S91":0,"S92":0,"S93":0,
"S94":0,"S95":0,"S96":0,"S97":0,"S98":0,"S99":0,"S100":0,"S101":0,"S102":0,"S103":0,"S104":0,"S105":0,"S106":0,"S107":0,"S108":0,"S109":0,"S110":0,"S111":0,"S112":0,
"S113":0,"S114":0,"S115":0,"S116":0,"S117":0,"S118":0,"S119":0,"S120":0,"S121":0,"S122":0,"S123":0,"S124":0,"S125":0,"S126":0,"S127":0},
"MyTimer":{"Acc":0,"Done":0,"Zero":1,"Timing":0,"Reset":1,"TT":0,"EN":0,"DN":0}
}
Reading specific fields of a structure from the PLC:
Format:
/data/json?MyStructField= <PLC structure>.field
Example:
<PLC IP Address>/data/json?MyMainDidItRun=$Main.RanThisScan&MyTimerZeroCurrent=T0.Acc
Response JSON record is an object containing the current data value of the specified field.
{
"MyMainDidItRun":1,
"MyTimerZeroCurrent":467
}
See Also:
The BRX CPU's On-board Web Server
The BRX CPU's HTTP-based REST API
Related Topics:
FTPGET - Retrieve File from Remote
HTTPCMD - HTTP Request / Response with Server
MQTTPUB - IoT Publish MQTT Topics
MQTTSUB - IoT Subscribe to MQTT Topics