Log ZCell contactor state

zcell-contactor-state.sh

#!/bin/bash
#
# Polls the ZCell BMS REST API once per second and prints the
# state of the Charge, Discharge and Energy Extrator (Strip)
# contactors if they've changed since the last poll.  Will
# run forever, or until all three contactors are open at the
# same time, whichever comes first.
# Requires `curl` and `jq`.
# 
# Note: this only looks at the first battery in the system
# (".list[0]" in the `jq` invocation).
#

if [ -z "$1" ]; then
	echo "Usage: $(basename $0) BMS_IP [POLL_INTERVAL]"
	exit 1
fi

STATUS_URL="http://${1}:3000/rest/1.0/status"
INTERVAL="${2:-1}"
LAST=""

echo "Polling ${STATUS_URL} at ${INTERVAL} second intervals"
while true ; do
	CONTACTORS="$(curl -s ${STATUS_URL} | jq -r '[(if .list[0].charge_contactor_state then "C" else "_" end), (if .list[0].discharge_contactor_state then "D" else "_" end), (if .list[0].strip_contactor_state then "E" else "_" end)] | join(" ")')"
	if [ "$CONTACTORS" != "$LAST" ] ; then
		echo -e "$(date --iso-8601=seconds)\t${CONTACTORS}"
		LAST="${CONTACTORS}"
	fi
	if [ "$CONTACTORS" = "_ _ _" ] ; then
		echo "All contactors open, exiting"
		break
	fi
	sleep $INTERVAL
done