# Heartbeat script having effects system wide

**URL:** <https://forum.inductiveautomation.com/t/heartbeat-script-having-effects-system-wide/21689>\
**Category:** Ignition\
**Created:** [January 4, 2019, 1:40pm UTC](https://forum.inductiveautomation.com/t/heartbeat-script-having-effects-system-wide/21689 "2019-01-04T13:40:19Z")\
**Posts on this page:** 1\
**Showing post:** 10

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [January 10, 2021, 5:15pm UTC](https://forum.inductiveautomation.com/t/heartbeat-script-having-effects-system-wide/21689/10 "2021-01-10T17:15:55Z")

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> [@Matrix\_Engineering](#):
>
> PLC counts to a certain value, once certain value is reached, Ignition resets back to 0

Eeek! No. Don't write from two directions. PLC should count and roll over. The low word of a PLC clock is fine. Ignition should count and roll over in its own timer event, writing to the appropriate OPC tag. Or write the low bits of Ignition's millisecond time to the OPC tag. It isn't important what the value is, just that it changes regularly.

Neither the OP nor @jdrichards70 shared their actual scripts, so there's no telling what the real problem is. Non-blocking writes should be used to prevent one broken device connection from killing the heartbeats to other device connections.

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