Contemporary Control Systems BASrouter Portable Installation Tips - Manual (Page 2)

MS/TP Considerations:
IMPORTANT: If BDT (described above) does not discover MS/TP devices, carefully read and
confirm the proper settings of all device and network parameters — and review the following:
SC Pin: This must be attached to the signal common used by all MS/TP devices (usually earth).
If this connection is not made, MS/TP communication will never be reliable .
MS/TP LED:
1. This flashes regardless of cable polarity, so double-check the MS/TP wiring polarity.
(Input connections are reverse-polarity protected.)
2. The BASrouter and all attached MS/TP devices must have the same baudrate . If the baud
rates differ, the BASrouter MS/TP LED may still flash.
3. If the MS/TP LED never glows — but the baud rate is proper — check your MS/TP wiring
and device settings.
Termination:
1. BASRT-B or BASRTLX-B: If the BASrouter is NOT at the end of the MS/TP bus, open its
case and adjust the bias/termination jumpers as explained in the product installation guide.
2. BASRTP-B: If it IS at the bus end, attach a 120-Ω resistor across the + and – terminals.
MaxMasters Value: Each device in the MS/TP network should have this set to the same value. If
this value is unknown, leave it at 127 in the BASrouter.
MS/TP Bus: Use 3-wire cabling if our router and other MS/TP devices share isolated transceivers.
MS/TP Devices: How many are attached? The more devices used, the more issues can arise.
EIA-485 technology supports 32 full-load devices. The BASrouter is a full-load device, so it can
share an MS/TP bus with up to 31 devices. More devices can be attached if they are half- or
quarter-load devices. The theoretical limit is 64 half-load devices or 128 quarter-load devices
(or a mix that yields the same load equivalence), but in reality MS/TP communication becomes
problematic when high device counts are attempted. We advise limiting the device count to 31
— even if they are less than full-load devices.
Address Duplication: If your bus communication is unstable or unreliable, check for this problem
(where same-addressed devices get the token and try to communicate simultaneously).
Status Screen: This is accessed via a button on the right side of the unit’s main configuration
screen. This screen lists many parameters that are updated when you manually refresh the
page. Some parameters are displayed only so you can take a screen capture to send to our
engineers for study. Other parameters can help you — even if you have no knowledge of the
BACnet standard. Read more at:
www.ccontrols.com/enews/0512story5.htm