Separate command from state
Receiving an HTTP response to a relay command does not by itself prove that the physical process completed. Read the output state after the command and, for critical processes, verify field feedback through a digital input.
Timeouts and retries
Set a bounded timeout for every request. Uncontrolled retries can repeat relay pulses. A safer client assigns an operation identifier, reads current state, and sends a command only when a change is required.
Credentials and network
Do not hard-code passwords in source code; use environment variables or a secure secret store. Keep the API reachable through a trusted LAN or VPN, never publish the device directly to the internet, and restrict the automation network with access rules.
Observability
Record request time, target device, channel, desired state, response, and error cause in structured logs. Exclude sensitive credentials. Health checks and alert thresholds make silent integration failures visible sooner.