TECSYSTEM NT579 User Manual

14
NT579-NT579 RS485
TECSYSTEM SHANGHAI
POLLING FREQUENCY
The max. time to give an answer to a calling never exceeds 1 second; therefore
we suggest not to use polling frequencies with lower duration.
CRC CALCULATION
This protocol includes 2 CRC-16 bytes in each transmission. The characteristic
polynomial (11000000000000101B) is used for the calculation and the result is
“hung” at the end of the package. The polynomial is used in the reverse order
with the most significant bit suppressed because useless for calculation.
PARAMETER DESCRIPTION
A - 16-bit register
AL - At low side
AH - At huigh side
i,j, - KWH METERS
(+) - EXCLUSIVE OR
Di - Frame data «i»th of the packet
N - number of byte of the packet excluded 2 belonging to CRC
G - Polynomial : 1010-0000-0000-0001
shr - right shift
ALGORITHM
1) 0xFFFF -> A
2) 0 -> i
3) 0 -> j
4) Di (+) AL -> AL
5) j +1 -> j
6) shr A
7) if carry then G (+) A -> A
8) if NOT j=8 then go to 5
9) i +1 -> i
10) if NOT i = N then go to 3
11) A -> in CRC (result is in the order L,H)
CODE 16
(10)
.
Request:
Slave address, code 16
(10)
, Starting address HI, Starting address LO, Num-
ber of Point HI, Number of Point LO, Byte count, Data HI, Data LO…….,
Crc LO, Crc HI.
The alarm thresholds (registers 3-4-5-6) are written only for channel L1

TECSYSTEM NT579 Specifications

General

Brand	TECSYSTEM
Model	NT579
Category	Controller
Language	English