Have you tried this one?
https://<nodename>:9060/ers/config/node/name/<instancename>accept=application/json&ERS-Media-Type=deploy.node.1.1&content-type=application/json
The bits in bold italic above are you site specific data items
We use it to determine which PAN is the current active one. The highlighted JSON value below shows that this node is the Primary active. Notice that this is ISE 2.4 and the values vary from previous ISE versions
{
"Node": {
"id": "aee5cb10-42d6-11e8-9914-0050568a2395",
"name": "ise-2-4-01",
"gateWay": "192.168.0.1",
"displayName": "ise-2-4-01",
"inDeployment": true,
"otherPapFqdn": "",
"ipAddresses": [
"192.168.0.221"
],
"ipAddress": "192.168.0.221",
"nodeServiceTypes": "SESSION,PROFILER,DEVICE ADMIN",
"primaryPapNode": true,
"papNode": true,
"pxGridNode": false,
"link": {
"rel": "self",
"href": "https://ise01:9060/ers/config/node/name/ise-2-4-01",
"type": "application/xml"
}
}
}