JANUARY 1998
CL512A-F
CL512A-M
Modular Current Loop Adapter
TX+
TXRX+
RX-
1
3
2
4
3
2
232 TO CL
CL TO 232
DTE
DTE
DCE
DTE
DCE
DCE
CL512
CUSTOMER
SUPPORT
INFORMATION
Order toll-free in the U.S.: Call 877-877-BBOX (outside U.S. call 724-746-5500)
FREE technical support 24 hours a day, 7 days a week: Call 724-746-5500 or fax 724-746-0746
Mailing address: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: info@blackbox.com
2
MODULAR CURRENT LOOP ADAPTER
TRADEMARKS USED IN THIS MANUAL
Any trademarks mentioned in this manual are acknowledged to be the property of
the trademark owners.
3
MODULAR CURRENT LOOP ADAPTER
Contents
Chapter Page
1. Specifications ..........................................................................................................4
2. Description..............................................................................................................5
3. Configuration and Installation ..............................................................................6
3.1 RS-232 Interface............................................................................................6
3.1.1 DCE or DTE Configuration ............................................................6
3.1.2 Connecting the RS-232 Device ........................................................6
3.2 Current-Loop Interface................................................................................7
3.2.1 Full-Duplex Operation ....................................................................8
3.2.2 Half-Duplex Operation..................................................................10
3.2.3 Connecting the Current-Loop Device ..........................................11
4
MODULAR CURRENT LOOP ADAPTER
Speed — Up to 19.2 Kbps
Maximum Distance — 1000 ft. (304.8 m)
Operation — Passive, 20-mA current loop, unipolar, mark=current,
space=no current
Interface — RS-232/V.24, DCE or DTE (switch-selectable), 20-mA
current loop
Connectors — RS-232: (1) DB25 male for CL512A-M, (1) DB25 female
for CL512A-F; Current Loop: (1) four-position screw
terminal strip and (1) RJ-11 (4-wire)
Enclosure — Metal
Power — +12 volts must be provided by EIA Interface (Pin 6
when unit is configured as a DTE, Pin 20 when
configured as a DCE); current provided by external
“active” device (20 mA, 24 VDC max.), optically isolated
for RS-232 signal protection
Size — 0.9" H x 2.1" W x 3" D (2.3 x 5.3 x 7.6 cm)
Weight — 2.1 oz. (59.5 g)
1. Specifications
5
MODULAR CURRENT LOOP ADAPTER
The Modular Current Loop Adapter connects current-loop equipment such as
industrial controllers and Data General computers to RS-232 equipment such as
modems, multiplexors, computers and terminals. The unit is a “passive” device:
this means it does not provide current for the current loop. The “passive” adapter
must connect to an “active” current-loop device. The “active” device provides the
20-mA current for the loop. (There can be only one active device in the current
loop.) The RS-232 interface of the attached equipment must provide a +12 voltage
on either pin 6 or pin 20 to power the adapter.
2. Description
6
MODULAR CURRENT LOOP ADAPTER
3.1 RS-232 Interface
3.1.1 DCE ORDTE C
ONFIGURATION
The adapter connects easily to an RS-232 device such as a DTE (terminal,
computer) or DCE (modem, line driver, multiplexor).
The attached RS-232 device supplies power to the adapter via a positive (+12)
voltage on the adapter’s pin 20 (if the unit is configured as DCE) or pin 6 (if the
unit is configured as DTE). Pinnings for both configurations are shown below.
DTE DCE
Pin 2 = TD (output) Pin 2 = TD (input)
Pin 3 = RD (input) Pin 3 = RD (output)
Pin 6 = DSR (input) Pin 20 = DTR (input)
Pin 7 = Signal Ground Pin 7 = Signal Ground
To configure the adapter, simply move the external switch to the DTE or DCE
position. If you are going to plug the adapter into a DTE, move the adapter switch
to the DCE position. If you are going to plug the adapter into a DCE, move the
adapter switch to the DTE position.
3.1.2 C
ONNECTING THE
RS-232 D
EVICE
To connect the adapter to the RS-232 device, simply plug the unit’s DB25
connector into your RS-232 equipment’s DB25 connector. (The unit is available in
both male and female versions to accommodate your equipment.)
3. Configuration and Installation
7
MODULAR CURRENT LOOP ADAPTER
3.2 Current-Loop Interface
Review the following pinning guidelines before you connect the twisted-pair cable
from your current-loop device to the adapter’s RJ-11 port or four-position screw
terminal. Figure 3-1 shows the pin positions for both connectors.
Figure 3-1. Pin Positions for RJ-11 and Terminal Screw Block.
Connections on the current-loop side of the adapter may be full- or half-duplex. In
full-duplex transmission, both the adapter and the current-loop device may send
and receive data simultaneously. In half-duplex transmission, only one device at a
time may send or receive data. Section 3.2.1 describes full-duplex connections and
Section 3.2.2 discusses half-duplex connections.
1234
1 2 3 4
RX-TX+TX-RX+ RX-RX+TX-TX+
8
MODULAR CURRENT LOOP ADAPTER
3.2.1 F
ULL-DUPLEXOPERATION
Table 3-1. Pinouts for Full-Duplex Current-Loop Connections
RJ-11 Modular Pinnings:
1 = RX+, connect to the TX+ of your device.
2 = TX-, connect to the RX- of your device.
3 = TX+, connect to the RX+of your device.
4 = RX-, connect to the TX- of your device.
Terminal Block Pinnings:
1 = TX+, connect to the RX+ of your device.
2 = TX-, connect to the RX- of your device.
3 = RX+, connect to the TX+ of your device.
4 = RX-, connect to the TX- of your device.
Typical full-duplex applications for the adapter are shown in Figures 3-2 and 3-3. In
Figure 3-2, the unit is connected to a DTE device. In Figure 3-3, the unit is
connected to a DCE device.
NOTE
When connected to a DTE device, the adapter does not output pins 5
(CTS), 6 (DSR), or 8 (CD). If your computer (DTE) needs these pins
before it can send data, you must use a short cable with the proper pin
configuration between the computer and the unit. This entails looping
pin 4 (RTS) or any other signal at 12 volts to pins 5, 6, and 8 on the side
connected to the computer.
When connected to a DCE device, the adapter does not output pins 4
(RTS) or 20 (DTR), which your modem may need before it can send data.
If your modem needs these pins, you must use a short cable with the
proper pin configuration between the modem and the unit. This involves
looping pin 8 (CD) or any other signal on the interface that is at +12 V to
pins 4 and 20 on the side connected to the modem.
9
MODULAR CURRENT LOOP ADAPTER
Figure 3-2. Full-Duplex DTE Operation.
Figure 3-3. Full-Duplex DCE Operation.
FULL-DUPLEX (4-WIRE)
2
3
7
20
1
2
3
4
TX+
TXRX+
RX-
RX+
RXTX+
TX-
CL512
DCE DTE
COMPUTER
(DTE)
ASYNC COMPUTER
(ACTIVE CURRENT LOOP DEVICE)
FULL-DUPLEX (4-WIRE)
2
3
6
7
1
2
3
4
TX+
TXRX+
RX-
RX+
RXTX+
TX-
CL512
DCE DTE
MODEM
(DCE)
ASYNC COMPUTER
(ACTIVE CURRENT LOOP DEVICE)
10
MODULAR CURRENT LOOP ADAPTER
3.2.2 H
ALF-DUPLEXOPERATION
Table 3-2. Pinouts for Half-Duplex Current-Loop Connections
RJ-11 Modular Pinnings*
3 = + Loop
Jumper 1 to 2
4 = - Loop
Terminal Block Pinnings
1 = + Loop
Jumper 2 to 3
4 = - Loop
*Half-duplex operation is not recommended for RJ-11 connections due to the
difficulty involved in crossing Jumpers 2 and 3.
Typical half-duplex applications for the adapter are shown in Figures 3-4 and 3-5.
In Figure 3-4, the unit is connected to a DTE device. In Figure 3-5, the unit is
connected to a DCE device.
NOTE
When connected to a DTE device, the adapter does not output pins 5
(CTS), 6 (DSR), or 8 (CD). If your computer needs these pins before it
can send data, you must use a short cable with the proper pin
configuration between the computer and the unit. This entails looping
pin 4 (RTS) or any other signal at +12 volts to pins 5, 6, and 8 on the side
connected to the computer.
When connected to a DCE device, the adapter does not output pins 4
(RTS) or 20 (DTR). If your modem needs these pins before it can send
data, you must use a short cable with the proper pin configuration
between the modem and the unit. This involves looping pin 8 (CD) or
any other signal on the interface that is at +12V to pins 4 and 20 on the
side connected to the modem.
11
MODULAR CURRENT LOOP ADAPTER
Figure 3-4. Half-Duplex DTE Operation.
Figure 3-5. Half-Duplex DCE Operation.
3.2.3 C
ONNECTING THECURRENT-LOOPDEVICE
If you’re using the RJ-11 port on the adapter, simply plug the cable from the
current-loop device into the RJ-11 port.
If you’re using the screw terminal, wrap one of the 2- or 4-wire twisted pairs from
the current-loop device around each of the screw terminals.
HALF-DUPLEX (2-WIRE)
2
3
7
20
1
2
3
4
TX+
RX-
RX+
TX-
CL512
DCE DTE
COMPUTER
(DTE)
ASYNC COMPUTER
(ACTIVE CURRENT LOOP DEVICE)
HALF-DUPLEX (2-WIRE)
2
3
6
7
1
2
3
4
TX+
RX-
RX+
TX-
CL512
DCE DTE
MODEM
(DCE)
ASYNC COMPUTER
(ACTIVE CURRENT LOOP DEVICE)
© Copyright 1998. Black Box Corporation. All rights reserved.
1000 Park Drive • Lawrence, PA 15055-1018 • 724-746-5500 • Fax 724-746-0746
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