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7

CHAPTER 3: Installation

3.1.4  CTS D

ELAY

When the transmitter of a device is first turned on, an unstable carrier signal
is transmitted for several milliseconds. If data was sent during this period, it
would be received as distorted information. Setting a CTS delay on the
LD485A-HS allows the communications link to settle down before data can be
sent.

LD485A-HS as DCE

When the LD485A-HS is configured as a DCE device (DIP shunt in position
XW1A), jumper W9 controls the amount of delay from the time RTS (jumper
W5 in the A-B position) is received true until CTS is asserted true. If W5 is in
the B-C position, CTS will be inhibited if an RS-485 carrier is present when
RTS is raised. To select a CTS delay period, set jumper W9 to the 0-, 10-, or
30-msec position. Regardless of the delay setting selected, when RTS goes
false, CTS will immediately go false. If jumper W9 is in the “ON” position,
CTS will follow RTS.

LD485A-HS as DTE

When the LD485A-HS is configured as a DTE device (DIP shunt in position
XW1B), CTS is not supported.

3.1.5  RS-485 D

RIVER

E

NABLE

The LD485A-HS’s RS-485 driver can be set to be enabled one of three ways: by
RS-232 control signals, by data, or constantly on.

Driver Enabled by RS-232 Control Leads

If your equipment raises CD or RTS, you can set the RS-485 driver to be
enabled by one of these leads. If your equipment does not have the capability
to raise CD or RTS, you will need to set the RS-485 driver to be enabled by
data or constantly enabled.

In order for an RS-232 control lead to enable the RS-485 driver, W15 must be
in position A-B and W9 must be set for 0, 10, or 30 ms.

• When the RS-232 port is selected as DTE (DIP shunt in the XW1B

position), the RS-485 driver will be enabled when CD (pin 8 of the 
RS-232 connector) goes true.

• When the RS-232 port is selected as DCE (DIP shunt in the XW1A

position), RTS enables the driver.

Summary of Contents for LD485A-HS

Page 1: ...der Black Box Corporation 1000 Park Drive Lawrence PA 15055 1018 Web site www blackbox com E mail info blackbox com SEPTEMBER 1999 ME837A R2 ME837AE ME837C R2 ME838A R2 ME838AE ME838C R2 BC00702 FA520A R2 LD485A HS LD485A HS Card LD485A HS Opto Isolated LD485A HS Isolated Card LD485A HS OPTO ISOLATED TX RX CD RTS PWR NORMAL DLB RX TX RTS CD DCE DTE LD485A HS TX RX CD RTS PWR NORMAL DLB RX TX RTS C...

Page 2: ... operated in a commercial environment Operation of this equipment in a residential area is likely to cause interference in which case the user at his own expense will be required to take whatever measures may be necessary to correct the interference Changes or modifications not expressly approved by the party responsible for compliance could void the user s authority to operate the equipment This ...

Page 3: ...4 3 1 2 Frame Ground Signal Ground 4 3 1 3 Half Full Duplex Operation 5 3 1 4 CTS Delay 7 3 1 5 RS 485 Driver Enable 7 3 1 6 Half Duplex Turnaround Delay 8 3 1 7 RS 485 Interface Terminated or Unterminated 8 3 1 8 Normal Loopback Operation 9 3 1 9 RS 485 Interface Line Biased Fail Safe 9 3 2 DCE Configuration DTE Configuration 10 3 3 Typical Applications 18 Appendix A Pinning 25 ...

Page 4: ...sparent to data Indicators 5 LEDs TX RX RTS CD and PWR Temperature Operating 32 to 122 F 0 to 50 C Storage 4 to 158 F 20 to 70 C Humidity 0 to 95 relative humidity noncondensing MTBF Approximately 180 000 hours ground benign environment Power PS154 for use with ME837A R2 ME838A R2 Input 120V 60 Hz 20W Output AC 17VCT 0 7A PS154E for use with ME837AE ME838AE Input 230V 50 Hz 20W Output AC 17VCT 750...

Page 5: ...eration Timeout Delay 0 15 0 7 2 7 or 70 msec for the RS 485 driver enabled by data feature Typical Speed Versus Distance 4 wire point to point 26 AWG twisted pair SPEED DISTANCE 1200 bps 4 miles 6 4 km 2400 bps 3 miles 4 8 km 4800 bps 2 3 miles 3 7 km 9600 bps 1 7 miles 2 7 km 19 200 bps 1 2 miles 1 9 km 38 400 bps 0 9 mile 1 4 km 64 000 bps 0 75 mile 1 2 km 115 Kbps 0 4 mile 0 6 km NOTE Speed an...

Page 6: ...electrical noise from your factory floor won t affect your office communications and the difference in ground potential between buildings won t damage your sensitive equipment Additional features include a manual loopback test to check the system wiring for both the RS 232 and RS 485 interfaces and transient protection on the RS 485 interface to help prevent damage due to voltage transients on the...

Page 7: ...3 Apply power PS154 or PS154E depending on which LD485A HS you have See Chapter 1 for more information 3 1 Jumper and Switch Configuration NOTE As you read this section refer to Tables 1 and 2 Table 1 page 11 lists DCE jumper settings and Table 2 page 16 lists DTE jumper settings 3 1 1 DTE DCE CONFIGURATION A DIP shunt is used to select DTE or DCE configuration For the LD485A HS to appear as a DTE...

Page 8: ...d circulating currents are limited to acceptable levels 3 1 3 HALF FULL DUPLEX OPERATION Jumper W8 selects half duplex or full duplex operation Set W8 to the HALF position for half duplex operation Set W8 to the FULL position for full duplex operation NOTE When the jumper W9 is in the ON position and jumper W15 is in the A B position the RS 485 driver is always turned on to enable transmission of ...

Page 9: ... W17 DRIVER ENABLE HOLD A 70ms B 7ms C 2ms D 0 7ms E 0 15ms B C A W19 B C A W15 A B RTS CD ENABLED B C DATA ENABLED W9 30 mesc 10 mesc 0 mesc ON A B RTS CTS B C RTS CTS CD W5 A B C W15 W8 A B C A B C D E A B C D E A W16 W8 A B 2 WIRE B C 4 WIRE W16 TURNAROUND A 0ms B 0 1ms C 1ms R49 W7 1 2 3 4 P2 O N O N BIAS TERM XW1A DCE TB1 XW1B DTE W18 A B C J1 T A T B R A R B ...

Page 10: ...TS will immediately go false If jumper W9 is in the ON position CTS will follow RTS LD485A HS as DTE When the LD485A HS is configured as a DTE device DIP shunt in position XW1B CTS is not supported 3 1 5 RS 485 DRIVER ENABLE The LD485A HS s RS 485 driver can be set to be enabled one of three ways by RS 232 control signals by data or constantly on Driver Enabled by RS 232 Control Leads If your equi...

Page 11: ...rrors The receiving device will need to ignore the first character received Driver Constantly Enabled 4 Wire Only The RS 485 driver can be constantly enabled by setting jumper W9 to the ON position 3 1 6 HALF DUPLEX TURNAROUND DELAY When operating in half duplex mode jumper W8 in the HALF position the LD485A HS adds a small delay each time it stops transmitting data and prepares to receive data Th...

Page 12: ...ed as terminated the amount of distortion could increase possibly causing errors in the data being transmitted 3 1 8 NORMAL LOOPBACK OPERATION The Normal Loopback switch S1 is a two position pushbutton switch extending through the front panel The Normal position permits normal operation of the LD485A HS The Loopback position allows data coming into the LD485A HS to be sent back out the same port T...

Page 13: ...rs and switches see Section 3 1 Figure 2 Simplified Functional Block Diagram DCE Operation RS 232 RECEIVER TD TXA TXB RS 485 DRIVER TX ENABLE RS 232 DRIVER ENABLE RS 485 RECEIVER RD CD DSR ON RX RTS DATA RECEIVED ENABLES RS 485 DRIVER CIRCUIT HALF DUPLEX TURNAROUND DELAY CIRCUIT CARRIER DETECT CIRCUIT CD CTS RXB RXA W17 W15 W8 W16 W9 W5 HALF FULL B C A A B C ON 30 msec 10 msec 0 msec RTS Opto Isol...

Page 14: ...1 in A position 2 Signal ground connected to frame ground Connected W7 is IN solder your own 100 ohm 1 2 watt resistor in place Not connected W7 is OUT 3 Half or full duplex operation Full duplex W8 in FULL position 4 wire A B Half duplex W8 in HALF position 2 wire B C 4 CTS delay Yes W9 in 0 ms position W9 in 10 ms position W9 in 30 ms position No W9 in ON position no delay CTS follows RTS ...

Page 15: ...9 in 30 ms position b RS 485 driver enabled by data W15 in B C position and Disable timeout delay W17 msec A 70 B 7 C 2 D 0 7 E 0 15 c RS 485 driver constantly enabled W9 in ON position 6 Half duplex turnaround delay W8 in HALF position and 0 msec turnaround delay W16 in position A 0 1 msec turnaround delay W16 in position B 1 msec turnaround delay W16 in position C 5 msec turnaround delay W16 in ...

Page 16: ...r unterminated Terminated S2 in TERM position Unterminated S2 in UNTERM position 8 Normal or loopback operation Normal mode S1 in Normal position Loopback mode S1 in Loopback position 9 RS 485 Interface Line Biased Fail S3 Off No line bias Safe Receive S3 On Line biased NOTE If line bias is on the RS 485 CD will ALWAYS be on ...

Page 17: ...14 LD485A HS and LD485A HS Opto Isolated Figure 3 Line Bias S2 shows the line termination when Term is selected S3 shows line bias when Bias is selected Rx S3 S2 5V S3 Tx ...

Page 18: ...ition will allow the CD input to enable the RS 485 driver When jumper W9 is in the ON position the CD input has no affect on the RS 485 driver RS 232 RECEIVER RD TXA TXB RS 485 DRIVER TX DTR ON DATA RECEIVED ENABLES RS 485 DRIVER CIRCUIT HALF DUPLEX TURNAROUND DELAY CIRCUIT CD W17 W15 W16 W9 A B ON 30 msec 10 msec 0 msec CD CTS DSR NOT USED NOT USED RX RS 232 DRIVER ENABLE RS 485 RECEIVER TD RTS R...

Page 19: ...Signal ground connected to frame ground Connected W7 is IN 100 ohm 1 2 watt resistor soldered in place Not connected W7 is OUT 3 Half or full duplex operation Full duplex W8 in FULL position 4 wire A B Half duplex W8 in HALF position 2 wire B C 4 CTS delay CTS not supported 5 Enable RS 485 driver a RS 485 driver enabled by W15 in A B position and RS 232 lead CD W9 in 0 ms position W9 in 10 ms posi...

Page 20: ... turnaround delay W8 in HALF position and 0 msec turnaround delay W16 in position A 0 1 msec turnaround delay W16 in position B 1 msec turnaround delay W16 in position C 5 msec turnaround delay W16 in position D 35 msec turnaround delay W16 in position E 7 RS 485 interface terminated or unterminated Terminated S2 in TERM position Unterminated S2 in UNTERM position 8 Normal or loopback operation a ...

Page 21: ...alf duplex connection with both LD485A HSs terminated by setting switch S2 to the TERM position Figure 6 shows a typical point to point 2 wire half duplex connection with both LD485A HSs terminated by setting switch S2 to the TERM position In a 4 wire point to point application each of the drivers on the two LD485A HSs may always be enabled without any adverse effects In a 2 wire point to point or...

Page 22: ...r Half Duplex Figure 6 Point to Point 2 Wire Half Duplex RS 232 DEVICE 1 TXA TXB RXA RXB RXA RXB TXA TXB RS 232 DEVICE 2 TERMINATED TERMINATED RS 232 DEVICE 1 TXA TXB RXA RXB RXA RXB TXA TXB RS 232 DEVICE 2 TERMINATED TERMINATED LD485 HS LD485 HS LD485 HS LD485 HS ...

Page 23: ...d by setting switch S2 to the TERM position These devices are the two devices that have the greatest cable length between them not necessarily the devices that are physically located the farthest apart See Figures 7 and 8 A resistor shown in the circuit indicates that the termination resistor has been selected via switch S2 Note that although Figures 7 and 8 show only four LD485A HS devices networ...

Page 24: ... Full Duplex RS 232 DEVICE 1 TERMINATED UNTERMINATED SUBORDINATE RS 232 DEVICE 2 UNTERMINATED SUBORDINATE RS 232 DEVICE 3 RS 232 DEVICE 4 TERMINATED RXA RXB TXA TXB TXA TXB RXA RXB RXA RXB TXA TXB RXA RXB TXA TXB MASTER MASTER LD485 HS LD485 HS LD485 HS LD485 HS ...

Page 25: ...re 8 Multipoint 2 Wire Half Duplex RS 232 DEVICE 1 TXA TXB RXA RXB TERMINATED UNTERMINATED RS 232 DEVICE 2 UNTERMINATED RS 232 DEVICE 3 RXA TXB RXA RXB RS 232 DEVICE 4 TERMINATED TXA TXB RXA RXB TXA TXB RXA RXB LD485 HS LD485 HS LD485 HS LD485 HS ...

Page 26: ...allation procedure follows Figure 9 Installation Procedure for the Multipoint Application in Figure 9 1 Set all the LD485A HSs for DCE operation jumper XW1 in position A 2 Connect a straight through cable from the RS 232 port on each LD485A HS to the RS 232 port on each of the PLCs 3 Set all the LD485A HSs for normal operation switch S1 in the Normal position 4 After a remote station has been addr...

Page 27: ...ontroller in our example so it would be wise to set the CTS Delay jumper W9 for 10 msec This allows the line to stabilize after a remote PLC becomes active but before it starts to transmit 8 Set jumper W9 on the LD485A HS connected to the industrial controller to the ON position This allows the industrial controller to transmit to the remote PLCs without having to wait for any delay period 9 Set j...

Page 28: ...CE 3 bb Receive Data Data From DCE 4 CA Request To Send Control To DCE 5 CB Clear To Send Control From DCE 6 CC Data Set Ready Control From DCE 7 AB Signal Ground Ground 8 CF Data Carrier Detect Control From DCE 9 DC Test Voltage 10 DC Test Voltage 11 Unassigned 12 SCF Secondary Data Control From DCE Carrier Detect 13 SCB Secondary Clear Control From DCE To Send Appendix A Pinning ...

Page 29: ... Data To DCE Data 15 DB Transmit Signal Timing From DCE Element Timing DCE 16 SBB Secondary Receive Data From DCE Data 17 DD Receiver Signal Timing From DCE Element Timing 18 Local Loopback Test To DCE 19 SCA Secondary Request Control To DCE To Send 20 CD Data Terminal Ready Control To DCE 21 CG Signal Quality Control From DCE Detector 22 CE Ring Indicator Control From DCE ...

Page 30: ...hart Pin Name Description TXA and TXB Data received by the LD485A HS at the RS 232 port is transmitted out of the unit over twisted pair wires via these two outputs The TX LED indicates the state of these two leads When the TXA lead is positive with respect to the TXB lead a zero is being transmitted the TX LED is lit RXA and RXB These are the received data inputs for the RS 485 port The status of...

Page 31: ...delay CTS inhibited if CD is present when RTS is raised W9 RTS CTS delay The time before the RS 485 driver is enabled and CTS is asserted after RTS is asserted The RS 485 driver is always enabled A 30 msec B 10 msec C 0 msec D ON W17 When W15 is in the B C Data Enabled position this is the time the RS 485 driver remains enabled after a low to high transition on the DATA line to prevent disabling t...

Page 32: ... 1 msec D 5 msec E 35 msec NOTE If the LD485A is configured Data Enabled W15 position B C and 2 wire W8 position B C then delays from W17 and W16 are cumulative S1 OUT Normal IN Loopback S2 OFF RS 485 Receiver Unterminated ON RS 485 Receiver Terminated S3 OFF Line Bias Off ON Line Bias On The Carrier Detect light will come on Default is 5 volts TB1 4 wire terminal block 1 Rx B 2 Rx A 3 Tx B 4 Tx A...

Page 33: ...1000 Park Drive Lawrence PA 15055 1018 724 746 5500 Fax 724 746 0746 Copyright 1999 Black Box Corporation All rights reserved ...

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