User manual

ProgrammingGuide

MarathonSeriesFA/FR 39

9ProgrammingGuide

Thissectionexplainsthesensor’scommunicationprotocol.Usethemwhenwritingcustomprograms

foryourapplicationsorwhencommunicatingwithyoursensorwithaterminalprogram.

9.1RemoteversusManualConsiderations

Since the sensor includes a local user interface, the possibility exists for a person to make manual

changes to parameter settings. To resolve conflicts between inputs to the sensor, it observes the

followingrules:

• Commandprecedence:themostrecentparameterchangeisvalid,whetheroriginatingfrom

manualorremote.

• If

amanualparameterchangeismade,thesensorwilltransmita“notification”stringtothe

host.(Notificationstringsaresuppressedinmultidropmode.)

• Amanuallockoutcommandisavailableintheprotocolssetsothehostcanrendertheuser

interface“displayonly,”ifdesired.



Allparameterssetviathe

2‐wayinterfaceareretainedinthesensor’snonvolatilememory.



When a unit is placed in multidrop mode its manual user interface is automatically

locked! It can be unlocked with the command XXXJ=U <CR>, where XXX is the

multidropaddress.

9.2CommandStructure

Protocols are the set of commands that define all possible communications with the sensor. The

commands are described in the following sections along with their associated ASCII command

charactersandrelatedmessageformatinformation.Typesofcommandsincludethefollowing:

1. Arequestforthecurrentvalueofaparameter

 Achangeinthesettingofaparameter

3. Defining the information contents of a string (either continuously output or periodically

polledattheoptionoftheuser)



Thesensorwillrespondtoeverycommandwitheitheran“acknowledge”ora“notacknowledge”

string.Acknowledgestringsbeginwiththeexclamation

mark!andareeitherverificationofaset

commandoraparametervalue.

Iftheunitisinmultidropmodethe3‐digitaddresscanbesentout

beforetheexclamationmark.

Forachangeinthesettingofa parameter,therangeofpossiblesettingvaluesisdefined,and,ifthe

host inputs a value outside the allowed range, an appropriate “error” response

 character shall be

transmittedbackbythesensor.



All commands must be entered in upper case (capital) letters. Also note that leading

andtrailingzerosarenecessary!