NEC NDA-30115-001 User Manual
Page 4
NDA-30115 Revision 1.0
Architecture
Property Management System - Communication Interface
Asynchronous Transmission
Line Control
Characteristics
Characteristics
The characteristics of the signals transmitted across the communications link are as
follows:
follows:
Table 2-1 Line Control Characteristics
Item
Conditions
Control Method
Contention method (point to point)
Operating Mode
Half duplex (if modems are used, set to full duplex)
Synchronization
Start-stop system
Data Rate
1200, 2400 or 4800 bits/second (bps)
Frame Contents
ASCII (7bits)
Error Control Method
VRC: Parity, LRC: BCC
Bit Transmission Order
Priority is given to low order bits.
Transmission Intervals
At each data generation. When a stream of information is
transmitted to the NEAX continuously, an interval of 0.5
seconds or more should be given between messages. Each
message must be delimited by the EOT code.
transmitted to the NEAX continuously, an interval of 0.5
seconds or more should be given between messages. Each
message must be delimited by the EOT code.
Priority Sequence
Primary office: NEAX
Secondary Office: PMS
Secondary Office: PMS
Stop bit
1 bit or 2 bits
Error Control
VRC: Even, odd or no parity.
LRC: (BCC) Exclusive OR of the message text, starting after the
STX, and ending with (and including) the ETX.
LRC: (BCC) Exclusive OR of the message text, starting after the
STX, and ending with (and including) the ETX.
Message Composition
One message constitutes one record; SOH, TTB and ETB are not
used.
used.
Message Length
Variable length, maximum of 128 characters (including STX and
ETX).
ETX).
Electrical Interface
EIA RS-232C electrical standard interface
Signal Form
EIA RS-404
Interface Distance
Maximum of 50 feet between the NEAX and the PMS when not
using a modem.
using a modem.
Word Framing
10 bits (1 start, 7 data, 1 parity, 1 stop) or 11 bits (1 start, 7 data,
1 parity, 2 stop)
1 parity, 2 stop)