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Black Box ME800A Plus, Instruction Manual

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Black Box ME800A Plus Instruction Manual Download Page 14

13

SHM-B PLUS ASYNC

3.3 Switch Settings

DTE/DCE S

WITCH

Refer to Figure 1 in this chapter. Switch S1 is used to
reverse the TD, RD, and hardware flow control lines on
the EIA-232 interface. This eliminates the need to swap
these signals in your EIA-232 cables. If you connect the
SHM-B to your equipment using a “straight-through” or
“2:2” cable, then S1 must be set to the opposite of your
device’s configuration. For example, if your device is
configured as DTE, select DCE on S1. If you use a null
modem, “2:3”, or “3:2” cable to connect the SHM-B to
your equipment, then the setting for S1 will be identical
to your equipment’s setting. Refer to your equipment’s
manual for information concerning its DTE/DCE
setting. Table 2 gives the EIA-232 pinning of the SHM-B
with the DTE/DCE switch in the DCE position.

Summary of Contents for ME800A Plus

Page 1: ...er 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 TD RD NORMAL LOOPBACK ...

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: ...vabo sótano mojado o cerca de una alberca etc 6 El aparato eléctrico debe ser usado únicamente con carritos o pedestales que sean recomendados por el fabricante 7 El aparato eléctrico debe ser montado a la pared o al techo sólo como sea recomendado por el fabricante 8 Servicio El usuario no debe intentar dar servicio al equipo eléctrico más allá a lo descrito en las instrucciones de operación Todo...

Page 4: ... contactos y receptáculos donde salen del aparato 14 El equipo eléctrico debe ser limpiado únicamente de acuerdo a las recomendaciones del fabricante 15 En caso de existir una antena externa deberá ser localizada lejos de las lineas de energia 16 El cable de corriente deberá ser desconectado del cuando el equipo no sea usado por un largo periodo de tiempo 17 Cuidado debe ser tomado de tal manera q...

Page 5: ...4 SHM B PLUS ASYNC TRADEMARKS USED IN THIS MANUAL Any trademarks mentioned in this manual are acknowledged to be the property of the trademark owners ...

Page 6: ...ble insulated by polyethylene with a mutual capacitance of 0 083 pf mile Shielded twisted pair cable will reduce the distance to one third of the table value due to the additional capacitance contributed by the cable s shielding Actual distances may vary depending on your specific operating equipment and the cable you use Protocol Asynchronous Operation 4 wire full duplex point to point Line Inter...

Page 7: ...eversed with pin 20 Connectors 1 DB25 female 1 4 screw terminal block 1 RJ 11 6 positions 6 contacts 1 4 position mini DIN jack Diagnostics Loopbacks provided by a front panel switch Analog loopback on a 4 wire loop and digital loopback on equipment interface EIA 232 Status Indication Two bi color LEDs indicate the status of the transmitter and receiver A green light indicates a low logic level 3 ...

Page 8: ... by a wall mounted power transformer No more than 16 Vrms is present in unit Primary 115 VAC 10 60 Hz 5 watts 12 watts max Primary 230 VAC 10 50 60 Hz Secondary 17 VAC 700 mA Size 1 3 H x 4 W x 4 2 D 3 3 x 10 7 x 11 3 cm Weight 1 4 lb 0 6 kg standalone including transformer ...

Page 9: ...monitor LEDs and a loopback switch The SHM B is available as a standalone version ME800A Plus The SHM B is designed to operate over a 4 wire metallic circuit Optimum performance is obtained with twisted pair cable see specifications Most types of twisted pair cable may be used often with little or no performance degradation The SHM B Async is designed for maximum operator safety There are no volta...

Page 10: ...1 shows the location of the terminal block and the RJ 11 jack a TERMINAL BLOCK Refer to Figure 2 to make the proper connections between two SHM B units using the terminal block NOTE Transmit TX on one modem is wired to Receive RX on the other modem Transmit TX is wired to Receive RX 1 Strip each of the four wires about 1 8 2 Loosen the screw terminals in the terminal block Insert the wires into th...

Page 11: ...ttom View Figure 2 Wiring Diagram Terminal Block TX TX RX RX RX RX TX TX S3 RTS DTR CONTROL RJ11 CONNECTOR TERMINAL BLOCK S1 DTE DCE DTE DCE EN DIS J1 RS 232 CONNECTOR POWER CONNECTOR S2 LOOPBACK RD LED TD LED TX TX RX RX SHM 1 SHM 2 ...

Page 12: ...er RJ 11 cable refer to Figure 3 A crossover cable has the RJ 11 tabs on the same side of the cable 2 Insert the RJ 11 cable into both local and remote modem s jack Figure 3 RJ 11 Jack CROSSOVER CABLE 1 TX 2 TX 3 RX 4 RX 5 6 6 5 RX 4 RX 3 TX 2 TX 1 Wiring Diagram SHM 2 SHM 1 ...

Page 13: ...Request To Send RTS Clear To Send CTS Data Set Ready DSR etc The SHM B generates levels for the control signals if you need to use them The table shows the pin connections at the SHM B Table 1 EIA 232 Pin Connections on SHM B Pin Number Signal Name 1 Protective Ground 2 Transmit Data Receive Data TD RD 3 Receive Data Transmit Data RD TD 4 Request to Send RTS DCD 5 Clear to Send CTS RTS 6 Data Set ...

Page 14: ...ment using a straight through or 2 2 cable then S1 must be set to the opposite of your device s configuration For example if your device is configured as DTE select DCE on S1 If you use a null modem 2 3 or 3 2 cable to connect the SHM B to your equipment then the setting for S1 will be identical to your equipment s setting Refer to your equipment s manual for information concerning its DTE DCE set...

Page 15: ...quest to Send RTS To DCE 5 Clear to Send CTS From DCE 6 Data Set Ready DSR From DCE 7 Signal Ground 8 Data Carrier Detect DCD From DCE 20 Data Terminal Ready DTR To DCE Pins 2 and 3 TD and RD and hardware flow control can be reversed using the DTE DCE switch S1 on the circuit board NOTE Configure each SHM B independently Your local and remote modems won t necessarily be configured the same ...

Page 16: ...rrectly Power is applied to the modems No computer devices are attached to the modems This forces DCD HIGH on the remote modem thus the remote modem knows to expect data In this state all systems are go The only way this state changes is if your equipment overrides this condition For example if your equipment drops DTR to a NEGATIVE signal your equipment s DTR being low will override the SHM B s D...

Page 17: ...F characters are used for handshaking control rather than hardware logic levels move the RTS DTR control switch to the DIS position Typically units that use software X ON X OFF flow control do not want RTS to affect DCD on the remote SHM B Moving the switch to the DIS position disables the RTS DCD relationship The only thing that will force DCD low with the switch in the DIS position is the absenc...

Page 18: ...r into its power source and into the SHM B Check the SHM B operation at both ends of the loop by pressing the LOOPBACK switch S2 Figure 4 Activating the LOOPBACK switch TD TX TX RD RX RX RS 232 SHM 1 in NORMAL mode RD RX RX TD TX TX RS 232 SHM 2 in NORMAL mode TD TX TX RD RX RS 232 SHM 1 in LOOPBACK mode RD RX RX TD TX TX RS 232 SHM 2 in NORMAL mode RX ...

Page 19: ...SHM B transmitter and receiver respectively Green indicates a LOW EIA 232 level and red indicates a HIGH EIA 232 level The LEDs will modulate as data is transmitted and received by the SHM B Remember that these LEDs are monitoring the actual received and transmitted signals not the TD and RD lines of the EIA 232 interface When the loopback test is completed press the LOOPBACK switch again to retur...

Page 20: ...onfiguration and flow control type hardware or software your EIA 232 cable pinouts and what if anything you have already done to correct the situation SYMPTOM LEDs do not light when power transformer is plugged into a wall outlet 1 Is the power connection loose Try moving or nudging the wall transformer 2 If the LEDs still do not light the SHM B may be defective SYMPTOM No data transfer in one or ...

Page 21: ...dem also Transmit TX must be wired to Receive RX Refer to Figure 2 during your inspection of the four wire circuit 3 Try a local test using the Loopback mode see Chapter 4 If there is no transfer check the setting of S1 and the wiring of your EIA 232 cable 4 The EIA 232 control signals are at the wrong levels Check the EIA 232 interface using a breakout box Pins 4 5 6 8 and 20 should all be HIGH t...

Page 22: ...smitted and or received data is full of errors garbled data 1 Check for reversal of polarity on the four wire connection Refer to Section 3 1 and Figure 2 2 Check communication settings baud rate parity word size on your computing equipment for consistency 3 Wire the SHM B units back to back eliminating the twisted pair see if you still have errors If you do have errors then test each SHM individu...

Page 23: ...n exceeded Refer to Chapter 1 for information about valid data transmission distances and bps rates 2 There is a poor quality loop four wire circuit Try using a different four wire circuit or rewire the existing circuit 3 Check the path of your four wire circuit for potential sources of interference fluorescent lighting electrical motors etc Such sources of electrical noise can provide an environm...

Page 24: ...egularities in the shield Also reconsider the cable s ratings for attenuation capacitance and impedance You may need to install a higher quality cable for your particular installation Your AC power source may be the culprit Check your AC power at the wall socket and confirm that it is within the range given in Chapter 1 SYMPTOM TD or RD indicator is steadily on red with no data attempting to pass ...

Page 25: ...1000 Park Drive Lawrence PA 15055 1018 724 746 5500 Fax 724 746 0746 Copyright 2000 Black Box Corporation All rights reserved ...

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