Tempco TEC-2500, Инструкция по эксплуатации, Страница: 70 / 108

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4–8 Data Communication
Two types of interfaces are available for data communication. These are the RS-485 and
RS-232 interfaces. Since RS-485 uses a differential architecture to drive and sense
signal instead of a single ended architecture which RS-232 uses, RS-485 is less sensitive
to noise and more suitable for communication over longer distances. RS-485 can
communicate without error over a distance of 1km while RS-232 is not recommended for
distances over 20 meters.
Using a PC for data communication is the most economical method. The signal is
transmitted and received through the PC communication port (generally RS-232). Since a
standard PC can't support an RS-485 port, a network adapter (such as TEC99927 or
TEC99928) has to be used to convert RS-485 to RS-232 for a PC. Up to 247 RS-485
units can be connected to one RS-232 port; therefore a PC with four comm ports can
communicate with 988 units.
Setup
Enter the setup menu.
Select FULL (full function) for FUNC.
Select 485 for COMM if RS-485 is required, or 232 if RS-232 is required. Select RTU
(i.e., Modbus protocol RTU mode ) for PROT. Set individual addresses for any units that
are connected to the same port. Set the baud rate (BAUD), data bit (DATA), parity bit
(PARI) and stop bit (STOP) so that these values are accordant with the PC setup
conditions.
NOTE: If the TEC-2500 is configured for RS-232 communication, the EI (event input) and
input 2 are disconnected internally. The unit can no longer perform event input function
(EIFN) or other input 2 functions.
When you attach an RS-232 module (TEC-102-103) to the connectors on the CPU board
(C250), you also need to modify jumpers J51 and J52 according to section 2-16. If you
use a conventional 9-pin RS-232 cable instead of TEC99014, the cable should be
modified for the proper operation of RS-232 communications according to section 2-16.
RS-485 Benefits:
Long distance
Multiple units
RS-232 Benefits:
Direct connection to a PC
RS-485 Setup
FUNC=FULL
COMM=485
PROT=RTU
ADDR=Address
BAUD=Baud Rate
DATA=Data Bit Count
PARI=Parity Bit
STOP=Stop Bit Count
RS-485 Terminals
RS-232 Setup
FUNC=FULL
COMM=232
PROT=RTU
ADDR=Address
BAUD=Baud Rate
DATA=Data Bit Count
PARI=Parity Bit
STOP=Stop Bit Count
RS-232 Terminals
RS-485 Terminals
12
13 TX1
TX2
RS-232 Terminals
12
13
11
TX1
TX2
COM