Control Techniques UD70, User Manual

Page: 134 / 154

UD70
Issue code: 70nu2
8-36 Features
8.13 Digital I/O ports
The
UD70
has two digital inputs and one digital output as standard. These
inputs and output are
TTL
logic (ie. 5V logic), and are made available on the
9-way
RS485
port connector, as follows:
Pin Description
1 RS485 isolated 0V
2 RS485 /TX
3 RS485 /RX
4 DIGIN0 (TTL digital input 0)
5 DIGIN1 (TTL digital input 1)
6 RS485 TX
7 RS485 RX
8 TTL digital output
9 Drive 0V
The digital
TTL
inputs are used in conjunction with the timer/counter unit.
In addition, they are also directly readable by a DPL program.
The digital
TTL
output can also be controlled directly from a DPL program.
The following virtual parameters give access to the
TTL
I/O:
Parameter Function
#86.01 Digital input 0 (DIGIN0)
#86.02 Digital input 1 (DIGIN1)
#86.03 Digital output
The inputs read 0 0 when at logic high (5V or unconnected), and 11 when at
logic low (0V).
The output is at logic high (5V) when 0 0 is written.
Warning
The digital output is rated at a maximum of 15 milliamps
(sink/source).
Connections to the digital inputs and outputs should be
kept as short as possible (0.5 metre (20 in) maximum
recommended). External buffering is required if longer
cable lengths are used, or interfacing is needed to
different logic levels.