Athena 6075 series, Инструкция по эксплуатации, Страница: 31 / 39

Standard and the 232 is the identification number for that particular Stan-
dard. The C designates the last revision made to the RS232 standard. The
purpose of this standard is to define the electrical characteristics for the
interfacing of ”data terminal equipment” and “data communications equip
ment”. The standard providesvoltage ranges for data and control signals to
provide proper transmission.
This module allows bi-directional data transfer via a three conductor cable
consisting of signal ground (pin 7). receive (input, pin 2) and transmit (out-
put, pin 3). It is recommended for less than fifty feet between computer/
terminal and instrument Note that multiple instruments cannot be tied to
the same port The module is optically isolated to eliminate ground Ioop
problems. Note that in a typical installation, “data out” of the computer/
terminal connects to "receive data" of the 6075 and "receive data" of the
computer/terminal connects to *‘data out” of the 6075. If shielded cable is
used it should be connected to frame ground at one end only. Signal ground
is connected at both ends. The RS232 module is configured for active
operation.
6.1.3 20 mA Current Loop
This module allows bi-directional data transfer via a current loop with each
instrument series connected within the loop (10 Units Maximum). The mod-
ule is “passive” i.e. an external current source is required. This is usually
available at the computer/terminal. Typically the receive and transmit sec-
tion of each instrument is series connected and inserted into the loop:
however a separate loop for receive and transmit may be used in the event
there is insufficient headroom in the energizing supply. For series transmit
and receive approximately two volts of headroom is taken for each instru-
ment on line. For operation with separate loops, approximately 1.5 volts is
taken for receive and 0.5 volts for transmit Care must be observed to insure
the polarity of connections is correct because current will still flow in the loop
if polarity is reversed making troubleshooting difficult Wiring connections
are: pin 3 = Transmitting Position (+), pin 4 = Transmit (-), pin 7 =
Receive (+), pin 8 = Receive
(-),
pins 5 and 9 are Frame Ground.
27