Schweitzer Engineering Laboratories SEL-421-4 - Page 1306

15.36
SEL-400 Series Relays Instruction Manual Date Code 20171006
Communications Interfaces
SEL M
IRRORED BITS Communication
Setting SPEED := SYNC (available only on the rear-panel serial ports for which
PROTO := MBA, MBB, MBGA, or MBGB) places the serial port in synchronous
(or externally-clocked) mode. The serial port hardware will synchronize transmit
and receive data (TX/RX) to a clock signal applied to the Pin 8 input at any effec-
tive data rate as high as 64000. This setting choice will suit certain synchronous
communications networks.
The relay uses the RBADPU setting to determine how long a channel error must
persist before the relay asserts RBADA or RBADB. The relay deasserts RBADA
and RBADB immediately when it no longer detects a channel error.
The relay uses the CBADPU setting to determine when to assert CBADA and
CBADB. If the short-term channel down time ratio exceeds CBADPU, the relay
asserts the appropriate CBAD bit.
The TXMODE setting provides compatibility with SEL devices that are not
SEL-400 series relays. The relay can send messages more quickly than the
SEL-300 series relays and other SEL devices can process these messages. This
could lead to loss of data and a failure to communicate properly. When you set
TXMODE to P, the relay sends new M
IRRORED BITS messages every 3 ms even if
the selected data speed (SPEED setting) would allow more frequent messages.
As a function of the settings for SPEED, TXMODE, and MBT, the message
transmission periods are shown in Table 15.26.
SPEED Data speed. Hidden and set to 9600 if
MBT := Y
300, 600, 1200, 2400, 4800,
9600, 19200, 38400, SYNC
9600
STOPBIT Stop bits. Hidden and set to 1 if MBT := Y 1, 2 1
Ta b l e 1 5. 25 M
IRRORED BITS Communications Protocol Settings (Sheet 1 of 2)
Name Description Range
TX_ID MIRRORED BITS communications ID of this
device
1–4
RX_ID M
IRRORED BITS communications ID of
device connected to this port
1–4 (must be different than
TX_ID)
RBADPU Outage duration to set RBAD 1–10000 seconds
CBADPU Channel unavailability to set CBAD 1–100000 parts per million
TXMODE Transmission mode
a
N (normal), P (paced)
MBNUM Number of M
IRRORED BITS communications
data channels used for logic bits
0–8
RMB1FL
b
RMB1 channel fail state 0, 1, P
RMB1PU
b
RMB1 pickup message count 1–8
RMB1DO
b
RMB1 dropout message count 1–8
•
•
•
•
•
•
RMB8FL
b
RMB8 channel fail state 0, 1, P
RMB8PU
b
RMB8 pickup message count 1–8
RMB8DO
b
RMB8 dropout message count 1–8
MBTIME M
IRRORED BITS time synchronize enable Y, N
Table 15.24 General Port Settings Used With M
IRRORED BITS Communications
(Sheet 2 of 2)
Name Description Range Default