FB_WriteWatchdog

FB_WriteWatchdog 1:

Writing of a watchdog signal to another ADS device (TwinCAT PLC, Bus Terminal Controller, ...).

The FB_WriteWatchdog function block cyclically writes the contents of a 32-bit counter into another ADS device. The counter is incremented every time the transmission is successful. The FB_CheckWatchdog function block can be used at the receiver to evaluate this signal. The receiver is addressed by means of the AMS-NetId and the port number (see also ADS Device Identification). The position within the receiver is specified by the index group/index offset or by the symbol name. Usually this is the input image or the flags area.

The period for tWachtdogTime should not be shorter than 1 second, to avoid transmitting the counter state too frequently. If 0 s is given for tWatchdogTime, the signal is not transmitted. Please also note the description of the function block FB_CheckWatchdog ().

If the input bEnable is set to FALSE, no further transfer of the watchdog signal takes place.

FB_WriteWatchdog 2: Inputs

VAR_INPUT
    bEnable          :  BOOL := FALSE;
    sNetId           :  T_AmsNetId;
    nPort            :  T_AmsPort;
    nIdxGrp          :  UDINT;
    nIdxOffs         :  UDINT;
    sVarName         :  STRING;
    tWatchdogTime    :  TIME := t#0s;
    bSendNow         :  BOOL;
END_VAR

Name

Type

Description

bEnable

BOOL

Enable function block.

sNetId

T_AmsNetID

AMS NetID of the ADS device to which the watchdog signal is to be transmitted.

nPort

T_AmsNetID

AMS port number of the ADS device to which the watchdog signal is to be transmitted.

nIdxGrp

UDINT

Index group within the ADS device to which the watchdog signal is to be transmitted.

nIdxOffs

UDINT

Index offset within the ADS device to which the watchdog signal is to be transmitted.

sVarName

STRING

Symbol name within the ADS device to which the watchdog signal is to be transmitted.

tWatchdogTime

TIME

Cycle time in which the watchdog signal is transmitted.

bSendNow

BOOL

The watchdog signal is transmitted immediately by a positive edge.

FB_WriteWatchdog 3: Outputs

VAR_OUTPUT
    bBusy     :  BOOL := FALSE;
    nLastCnt  :  UDINT := 0;
    bError    :  BOOL := FALSE;
    nErrorId  :  UDINT := 0;
END_VAR

Name

Type

Description

bBusy

BOOL

The transmission is active.

nLastCnt

 

BOOL

Most recently transmitted counter value.

bError

BOOL

An error occurred during the transmission.

nErrorId

UDINT

ADS error number if an error has occurred.

Requirements

Development environment

required TC3 PLC library

TwinCAT v3.0.0

Tc2_DataExchange