ltm monitor http /Common/ws-healthmonitor_HTTP1.1_200-OK_http {
defaults-from /Common/http
description "Custom monitor - requests resource from specific sub folder."
destination *:*
interval 5
recv "HTTP/1.(0|1) 200 OK"
send "HEAD /ws/healthmonitor HTTP/1.1\\r\\nHost:\\r\\n\\r\\n"
time-until-up 0
timeout 16
}
Note that I haven't specified the port as the pool already specifies it (I prefer to keep monitors as generic as possible).
To check for the string "PASS" I would create a second monitor. It's possible to use a single one, but it makes troubleshooting more difficult (e.g. if there's a 200 but not "PASS").