diff --git a/coordinator/coordinator.lua b/coordinator/coordinator.lua
index c877eb6..f4c8b69 100644
--- a/coordinator/coordinator.lua
+++ b/coordinator/coordinator.lua
@@ -279,11 +279,12 @@ function coordinator.comms(version, nic, sv_watchdog)
     -- send an API establish request response
     ---@param packet scada_packet
     ---@param ack ESTABLISH_ACK
-    local function _send_api_establish_ack(packet, ack)
+    ---@param data any?
+    local function _send_api_establish_ack(packet, ack, data)
         local s_pkt = comms.scada_packet()
         local m_pkt = comms.mgmt_packet()
 
-        m_pkt.make(MGMT_TYPE.ESTABLISH, { ack })
+        m_pkt.make(MGMT_TYPE.ESTABLISH, { ack, data })
         s_pkt.make(packet.src_addr(), packet.seq_num() + 1, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
         nic.transmit(config.PKT_Channel, config.CRD_Channel, s_pkt)
@@ -493,7 +494,8 @@ function coordinator.comms(version, nic, sv_watchdog)
                                 local id = apisessions.establish_session(src_addr, firmware_v)
                                 coordinator.log_comms(util.c("API_ESTABLISH: pocket (", firmware_v, ") [@", src_addr, "] connected with session ID ", id))
 
-                                _send_api_establish_ack(packet.scada_frame, ESTABLISH_ACK.ALLOW)
+                                local conf = iocontrol.get_db().facility.conf
+                                _send_api_establish_ack(packet.scada_frame, ESTABLISH_ACK.ALLOW, { conf.num_units, conf.cooling })
                             else
                                 log.debug(util.c("API_ESTABLISH: illegal establish packet for device ", dev_type, " on pocket channel"))
                                 _send_api_establish_ack(packet.scada_frame, ESTABLISH_ACK.DENY)
diff --git a/coordinator/iocontrol.lua b/coordinator/iocontrol.lua
index 2bd3a95..c91e24d 100644
--- a/coordinator/iocontrol.lua
+++ b/coordinator/iocontrol.lua
@@ -67,6 +67,7 @@ function iocontrol.init(conf, comms, temp_scale)
     -- facility data structure
     ---@class ioctl_facility
     io.facility = {
+        conf = conf,
         num_units = conf.num_units,
         tank_mode = conf.cooling.fac_tank_mode,
         tank_defs = conf.cooling.fac_tank_defs,
diff --git a/pocket/pocket.lua b/pocket/pocket.lua
index 402bd19..0d3b8da 100644
--- a/pocket/pocket.lua
+++ b/pocket/pocket.lua
@@ -126,7 +126,7 @@ function pocket.comms(version, nic, sv_watchdog, api_watchdog)
 
     -- attempt coordinator API connection establishment
     local function _send_api_establish()
-        _send_crd(MGMT_TYPE.ESTABLISH, { comms.version, version, DEVICE_TYPE.PKT })
+        _send_crd(MGMT_TYPE.ESTABLISH, { comms.version, version, DEVICE_TYPE.PKT, comms.api_version })
     end
 
     -- keep alive ack to supervisor
@@ -252,7 +252,7 @@ function pocket.comms(version, nic, sv_watchdog, api_watchdog)
     ---@param max integer?
     ---@return boolean
     local function _check_length(packet, length, max)
-        local ok = util.trinary(max == nil, packet.length == length, packet.length >= length and packet.length <= max)
+        local ok = util.trinary(max == nil, packet.length == length, packet.length >= length and packet.length <= (max or 0))
         if not ok then
             local fmt = "[comms] RX_PACKET{r_chan=%d,proto=%d,type=%d}: packet length mismatch -> expect %d != actual %d"
             log.debug(util.sprintf(fmt, packet.scada_frame.remote_channel(), packet.scada_frame.protocol(), packet.type))
@@ -322,7 +322,7 @@ function pocket.comms(version, nic, sv_watchdog, api_watchdog)
                                     log.warning("pocket coordinator KEEP_ALIVE trip time > 750ms (" .. trip_time .. "ms)")
                                 end
 
-                                log.debug("pocket coordinator TT = " .. trip_time .. "ms")
+                                -- log.debug("pocket coordinator TT = " .. trip_time .. "ms")
 
                                 _send_api_keep_alive_ack(timestamp)
 
@@ -428,7 +428,7 @@ function pocket.comms(version, nic, sv_watchdog, api_watchdog)
                                     log.warning("pocket supervisor KEEP_ALIVE trip time > 750ms (" .. trip_time .. "ms)")
                                 end
 
-                                log.debug("pocket supervisor TT = " .. trip_time .. "ms")
+                                -- log.debug("pocket supervisor TT = " .. trip_time .. "ms")
 
                                 _send_sv_keep_alive_ack(timestamp)
 
diff --git a/pocket/startup.lua b/pocket/startup.lua
index 8400e3b..622ee78 100644
--- a/pocket/startup.lua
+++ b/pocket/startup.lua
@@ -18,7 +18,7 @@ local iocontrol = require("pocket.iocontrol")
 local pocket    = require("pocket.pocket")
 local renderer  = require("pocket.renderer")
 
-local POCKET_VERSION = "v0.7.4-alpha"
+local POCKET_VERSION = "v0.7.5-alpha"
 
 local println = util.println
 local println_ts = util.println_ts