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cmseaton42 / node-ethernet-ip

A Lightweight Ethernet/IP API written to interface with Rockwell ControlLogix/CompactLogix Controllers.
MIT License
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Changed Event is missed for previously written tags #70

Open PeterChristen577 opened 4 years ago

PeterChristen577 commented 4 years ago

Changed Event is missed for previously written tags.

Current Behavior

When a tag is written to the PLC, in the following read cycles is no Changed Event produced.

Expected Behavior

A Changed Event is also produced for tags previously written to the PLC.

Possible Solution (Optional)

In file /src/tag/index.js remove line (574):

    unstageWriteRequest() {
        const { tag } = this.state;
        tag.stage_write = false;
        //tag.controllerValue = tag.value;
    }

Context

If node-ethernet-ip is used in Node-RED and eth-ip in and eth-ip out nodes are connected to the same PLC tag, the value is properly written to the PLC but cannot be read back. The reasons for this behaviour are:

  1. In unstageWriteRequest the value of tag.controllerValue is already updated to the new value.
  2. In controller_value the comparison (line 239) if (newValue !== this.state.tag.controllerValue) does not see a difference and there no Changed Event has been emitted.
  3. In Node-RED no message is generated at eth-ip in node.

Steps to Reproduce (for bugs only)

  1. In Node-Red, create a small flow consisting in: numeric to eth-ip in and eth-ip out to text. Both eth-ip nodes are linked to the same PLC DINT tag. Screenshot: Flow
  2. Run it and change the value of numeric node (input) on the dashboard.
  3. Check if the value for the text node (output), it does not change. Dashboard

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