Setting the Switches
18
Data Communications Module, 2nd Edition, 2/03
Protocol Selection:
Positions 1 and 2 on SW3 select the D2–DCM protocol and the master
or slave settings. The D2–DCM primarily uses two protocols,
Direct
NET and MODBUS
RTU protocol. Here’s some information to help you choose.
Communications Port for
Direct
SOFT32 Programming:
If you plan to program the CPU
through the D2–DCM, then you can use either
Direct
NET protocol or our proprietary
protocol, called K-sequence. Although it is not listed in the switch settings, K-sequence is
also available whenever the D2–DCM is set for
Direct
NET slave operation.
Computer or Operator Interface:
If you’re using the D2–DCM to connect a computer or
operator interface, check your documentation to see which protocol is being used. Since the
D2–DCM is always a slave station when it’s connected to a computer or operator interface,
you should select
Direct
NET slave or MODBUS
RTU slave. Note, there are also a handful
of operator interfaces that have been designed to use our proprietary K-sequence protocol. If
you have one of these, or if you need to use K-sequence for some reason, make sure you set
the D2–DCM for
Direct
NET Slave operation. Peer to Peer works in Hexadecimal mode only.
Direct
NET
Master / Slave:
In a
Direct
NET master / slave network, one D2–DCM should be
set as a master and the rest should be set as slaves.
Direct
NET
Peer as Master:
This is a variation of the master / slave protocol and should be
selected when you only have two stations that can each initiate requests. Each station must
have a D2–DCM as the network interface.
MODBUS
RTU Slave:
The D2–DCM can also be a MODBUS
slave (in the RTU or HEX
mode). The D2–DCM cannot be a MODBUS
master station. If you’re going to use
MODBUS
, make sure your software package supports the DL205 products. See Appendix
C for more information.
Communication Timeout:
Position 3 on SW3 selects the communication timeout. For most
cases, you should leave this switch in the OFF position. Communication Timeout Disable is
normally used
only
if you’re developing your own
Direct
NET programs. By disabling the
timeout, you can send one
Direct
NET component without any communication timeout
problems. If you have this timeout disabled and a communication error does occur, you must
restart communications by sending a retry or an End of Transmission (EOT) command. If you
want to know more, see the
Direct
NET manual for details.
ASCII / HEX Mode:
Position 4 on SW3 selects between ASCII and HEX modes of data
representation. If you want the fastest communication possible, use HEX mode, which is the
default. The difference is in the way the data is represented. The same data is twice as long in
ASCII format, so if there’s more data, it takes longer to transfer. If you have a device on the network
that requires ASCII mode, then set the switch for ASCII mode, otherwise, use HEX mode.
Baud Rate:
Positions 1 – 3 on SW5 are used to set the baud rate for the D2–DCM. There are
eight baud rate selections available ranging from 300bps to 38.4Kbps.
All stations must
have the same baud rate before the communications will operate correctly.
Usually,
you should use the highest baud rate possible unless noise problems appear. If noise
problems appear, try reducing the baud rates.
Parity:
Position 4 on SW5 selects between the two parity options, odd or none. If you’re using
all DL205 equipment, you should use odd parity. Odd parity uses eleven bits total (1 start bit, 8
data bits, 1 stop bit, and 1 parity bit).
Some devices require no parity, which uses only 10 bits (1 start bit, 8 data bits, and 1 stop bit).
Self-Test:
Position 5 on SW5 selects the factory self-test and should always be switched off.
If the self-test is on, the module will not operate correctly.
Response Delay Time:
Positions 6–8 on SW4 set the response delay time. The delay time
specifies the amount of time the D2–DCM waits to send the data after it has raised the RTS
signal line. This is normally set to 0, and is typically only adjusted if you are using the
D2–DCM with a radio modem. If you are using the D2–DCM with a radio modem, check your
modem documentation to help you choose the proper setting. Also, if you’re considering the
use of a modem, check out Appendix D. It may be of some help.
Содержание D2-DCM
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Страница 37: ...1A Cable Diagrams...
Страница 47: ...Data Communications Module 2nd Edition 2 03 B RLL Communications Programs...
Страница 58: ...Data Communications Module 2nd Edition 2 03 C Using the D2 DCM with MODBUS...
Страница 67: ...Data Communications Module 2nd Edition 2 03 D Using the D2 DCM with Modems...
