Functionality; Technical Data - Hitachi 670 Series Application Manual

Section 5
Communication set-up
Table 23:
Pin number
1
2
3
4
6
8
9
10
11
13
5,7,12,14,15
5.4.3

Functionality

The data format is HDLC. The speed for the transmission of the messages used is 64 kbit/s.
A maximum of 10 meter of cable is allowed to ensure the quality of the data (deviation from X.21
standard cable length).
Synchronization
The X.21 LDCM works like a DTE (Data Terminal Equipment) and is normally expecting
synchronization from the DCE (Data Circuit Equipment). The transmission is normally synchronized
to the Signal Element Timing signal when a device is a DTE. When the signal is high it will read the
data at the receiver and when the signal is low it will write data to the transmitter. This behaviour can
be inverted in the control register.
Normally an external multiplexer is used and it should act like the master.
When two X.21 LDCM is directly communicating with each other one must be set as a master
generating the synchronization for the other (the slave). The DTE Signal Element Timing is created
from the internal 64 kHz clock.
The Byte Timing signal is not used in Hitachi Energy devices.
5.4.4

Technical data

Table 24:
Quantity
Connector, X.21
Connector, ground selection
Standard
Communication speed
Insulation
Maximum cable length
70
Pinout for the X.21 communication connector
Signal
Shield (earth)
TXD A
Control A
RXD A
Signal timing A
Earth
TXD B
Control B
RXD B
Signal timing B
Not used
Galvanic X.21 line data communication module (X.21-LDCM)
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Range or value
Micro D-sub, 15-pole male, 1.27 mm (0.050") pitch
2 pole screw terminal
CCITT X21
64 kbit/s
1 kV
10 m
Communication set-up, 670/650 series
1MRK505382-UEN Rev. K
GUID-4512904E-08D1-47EC-B005-E66170CEB130 v4
GUID-83EC40D0-ABCF-4292-B3DF-155C3A556B76 v4
Application Guide