7
The 681 can be connected to a Building
Automation System to automatically operate a
snow melting System . The BAS is the system
master and the 681 the system slave . BACnet
MS/TP communications uses a RS-485 connec-
tion . Use 18 AWG shielded twisted pair cable .
The maximum cable length is dependent on the
baud rate and whether terminating resistors are
installed . Refer to the BAS Integration Manual
IS-T-681 for details on the maximum recom-
mended cable length .
• Connect the A (-) terminal on the BAS network
to the RS-485 A (-) terminal 8 .
• Connect the B (+) terminal on the BAS network
to the RS-485 B (+) terminal 9 .
• Connect the ground (G) on the BAS network to
the RS-485 Ref . terminal 10 .
Communication Wiring
The 681 is shipped pre-programmed with com-
mon settings . The 681 has an “Installer” access
level that allows full access to all settings and a
“User” access level that restricts the number of
settings available . The 681 defaults is the “User”
access .
To change to the “Installer” access level:
Step 1:
Press the gear button .
Step 2:
Press the Toolbox menu .
Step 3:
Press Access Level menu .
Step 4:
Select Installer and press save and
back button .
Access Levels