22
Field Wiring
4.4
Field Bus Connection and OpenBAS-ACC-DB9
Figure 17 Field bus connection
This port allows the field replacement of the RS-485 module with the OpenBAS-ACC-RS485
optically isolated RS-485 module or OpenBAS-ACC-RS232 conversion module. See section
3.3.1 on page 11.
To avoid intermittent communication blackouts, the isolation provided by the OpenBAS-ACC-
RS485 module is highly recommended for noisy environments, and to prevent damage to the
boards in extreme cases, especially if the OpenBAS-HV-NX4AO controller is inside an
enclosure containing high voltage wiring.
4.4.1 OpenBAS-ACC-DB9
OpenBAS-ACC-DB9 is a DB9 adapter which is installed in the field bus port.
4.5
Networking
Figure 18 shows 3 controllers networked with RS-485.
•
22 AWG twisted pair
•
Maximum length: 1219.2 m (4000 feet)
•
Mircom recommends shielded cable
Ref1
D1+
D1-
