ASSURED PCI-COM485-4 Official ACCES I O Distributor and Integrator User Manual

The information in this document is provided for reference only. ACCES does not assume any liability arising out of the application or use of the information or products described herein.
This document may contain or reference information and products protected by copyrights or patents and does not convey any license under the patent rights of ACCES, nor the rights of others.

IBM PC, PC/XT, and PC/AT are registered trademarks of the International Business Machines Corporation.
Printed in the USA. Copyright 2000, 2005 by ACCES I/O Products Inc., 10623 Roselle Street, San Diego, CA 92121. All rights reserved.

WARNING!! ALWAYS CONNECT AND DISCONNECT YOUR FIELD CABLING WITH THE COMPUTER POWERED OFF. ALWAYS TURN THE COMPUTER POWER OFF BEFORE INSTALLING A CARD.
CONNECTING AND DISCONNECTING CABLES, OR INSTALLING CARDS INTO A SYSTEM WITH THE COMPUTER OR FIELD POWER ON, MAY CAUSE DAMAGE TO THE I/O CARD AND WILL VOID ALL WARRANTIES, IMPLIED OR EXPRESSED.

Warranty

Before shipment, ACCES equipment is thoroughly inspected and tested to applicable specifications. However, should equipment failure occur, ACCES assures its customers that prompt service and support will be available.
All equipment originally manufactured by ACCES that is found to be defective will be repaired or replaced, subject to the following considerations.

Terms and Conditions

If a unit is suspected of failure, contact ACCES’ Customer Service department. Be prepared to give the unit model number, serial number, and a description of the failure symptom(s). We may suggest some simple tests to confirm the failure. We will assign a
Return Material Authorization (RMA) number which must appear on the outer label of the return package. All units/components should be properly packed for handling and returned with freight prepaid to the ACCES designated Service Center, and will be returned to the customer’s/user’s site freight prepaid and invoiced.

Coverage

First Three Years: Returned unit/part will be repaired and/or replaced at ACCES option with no charge for labor or parts not excluded by warranty. Warranty commences with equipment shipment.
Following Years: Throughout your equipment’s lifetime, ACCES stands ready to provide on-site or in-plant service at reasonable rates similar to those of other manufacturers in the industry.

Equipment Not Manufactured by ACCES

Equipment provided but not manufactured by ACCES is warranted and will be repaired according to the terms and conditions of the respective equipment manufacturer’s warranty.

General

Under this Warranty, liability of ACCES is limited to replacing, repairing or issuing credit (at ACCES discretion) for any products which are proved to be defective during the warranty period.
In no case is ACCES liable for consequential or special damage arising from the use or misuse of our product.
The customer is responsible for all charges caused by modifications or additions to ACCES equipment not approved in writing by ACCES or, if in ACCES opinion the equipment has been subjected to abnormal use.
Abnormal use, for purposes of this warranty, is defined as any use to which the equipment is exposed other than that use specified or intended, as evidenced by purchase or sales representation.
Other than the above, no other warranty, expressed or implied, shall apply to any and all such equipment furnished or sold by ACCES.

Introduction

This Serial Interface Card was designed for effective multipoint transmission in the RS485 (EIA-485) protocol. The card is 6.0 inches long and may be installed in 5-volt PCI-bus slots of IBM PC or compatible computers.

The card features four independent, asynchronous RS485 serial ports, type 16550 buffered UARTS, and, for Windows compatibility, automatic control to transparently enable/disable the transmission drivers.
There are two I/O connector options. The standard model includes two 9-pin male connectors on the card mounting bracket plus a second mounting bracket with two more 9-pin male connectors with ribbon cables to connect them to headers on the card.
Model S1 includes a single 25-pin connector on the mounting bracket plus a “spider” or breakout cable that terminates in four 9-pin D-type connectors.

RS485 Balanced Mode Operation

The card supports RS485 communications and uses differential balanced drivers for long-range and noise immunity. RS485 operation involves switchable transceivers and the ability to support multiple devices on a single “party line”.
The RS485 specification defines a maximum of 32 devices on a single line. The number of devices served on a single line can be expanded by the use of “repeaters”.

RS485 communications require that one transmitter supply a bias voltage to ensure a known “zero” state when all transmitters are off. Also, receiver inputs at each end of the network should be terminated to eliminate “ringing”.
The card supports biasing by default and supports termination by jumpers on the card. If your application requires the transmitter to be unbiased, please contact the factory.

COM Port Compatibility

Type 16550 UARTs are used as the Asynchronous Communication Element (ACE). These have a 16-byte transmit/receive buffer to protect against lost data in multitasking operating systems, while maintaining 100 percent compatibility with the original IBM serial port. The system assigns the address(es).
A crystal oscillator is located on the card. This oscillator ensures precise selection of baud rate up to 115,200 or, by changing a jumper, up to 460,800.
The driver/receiver used, the SN75176B, is capable of driving extremely long communication lines at high baud rates.

It can drive up to +60 mA on balanced lines and receive inputs as low as 200 mV differential signal superimposed on common mode noise of +12 V or -7 V. In case of communication conflict, the driver/receivers feature thermal shutdown.

Communication Mode

This card supports Half-Duplex communications with a 2-wire cable connection. Half-Duplex allows traffic to travel in both directions, but only one way at a time.

RS485 communications commonly use the Half-Duplex mode since they share only a single pair of wires.

Baud Rate Ranges

The card has capability for two baud rate ranges and you can select which you wish to use on a port-by-port basis. One range is up to 115,200 baud applications and the other is up to 460,800 baud.

Auto-RTS Transceiver Control

In RS485 communications, the driver must be enabled and disabled as needed, allowing all cards to share a two-wire cable. The card controls the driver automatically. With automatic control, the driver is enabled when data is ready to be transmitted.
The driver remains enabled for one additional character’s transmission time after data transfer is complete, and then is disabled.

The receiver is also normally enabled, then disabled during RS485 transmissions, and then re-enabled after transmission is completed (plus one character transmission time). The card automatically adjusts its timing to the baud rate of the data.
(Note: Thanks to the automatic control feature, the card is ideal for use in WIN95/98/NT applications)

Specifications

Communications Interface

I/O Connection: 9-pin D-sub connectors.
Serial Ports: Four shielded male D-sub 9-pin IBM AT style connectors compatible with RS485 specifications. (Note: On model S01, an external “spider” or breakout cable terminates with four female D-sub 9-pin connectors.)
Character length: 5, 6, 7, or 8 bits.

Parity: Even, odd, or none.
Stop Interval: 1, 1.5, or 2 bits.
Serial Data Rates: Up to 115,200 baud, Asynchronous, A faster range of rates, up to 460,800, is achieved by jumper selection on the card. Type 16550 buffered UART.

Address: Continuously mappable within the 0000 to FFFF (hex) range of PCI bus addresses (Conforms to PCI Specification 2.1).
Receiver Input Sensitivity: +200 mV, differential input.
Common Mode Rejection: +12V to 7V.

Transmitter Output Drive Capability: 60 mA, with thermal shutdown.

Environmental

Operating Temperature Range: 0 °C. to +60 °C.

Storage temperature Range: -50 °C. to +120 °C.
Humidity: 5% to 95%, non-condensing.
Power Required: +5VDC at 125 mA typical, –12VDC at 5 mA typical, +12VDC at 5 mA typical, 750 mW total power consumption.

Size: 7.8″ long (198 mm) by 3.9″ (99 mm).

Installation

A printed Quick-Start Guide (QSG) is packed with the card for your convenience. If you’ve already performed the steps from the QSG, you may find this chapter to be redundant and may skip forward to begin developing your application.
The software provided with this card is on CD and must be installed onto your hard disk before use. To do this, perform the following steps as appropriate for your operating system.

Configure Card Options via Jumper Selection

Before installing the card into your computer, carefully read Chapter 3: Option Selection of this manual, then configure the card according to your requirements and protocol (RS-232, RS-422, RS-485, 4-wire 485, etc.).
Our Windows-based setup program can be used in conjunction with Chapter 3 to assist in configuring jumpers on the card, as well as provide additional descriptions for usage of the various card options (such as termination, bias, baud rate range, RS-232, RS-422, RS-485, etc.).

CD Software Installation

The following instructions assume the CD-ROM drive is drive “D”. Please substitute the appropriate drive letter for your system as necessary.

DOS

Place the CD into your CD-ROM drive.
Typeto change the active drive to the CD-ROM drive.
Typeto run the install program.

Follow the on-screen prompts to install the software for this board.

WINDOWS

Place the CD into your CD-ROM drive.

The system should automatically run the install program. If the install program does not run promptly, click START | RUN and type, click OK, or press.
Follow the on-screen prompts to install the software for this board.

LINUX

Please refer to linux.htm on the CD-ROM for information on installing under Linux.
- Note: COM boards can be installed in virtually any operating system. We do support installation in earlier versions of Windows, and are very likely to support future versions as well.
- Caution! * ESDA single static discharge can damage your card and cause premature failure!
- Please follow all reasonable precautions to prevent a static discharge, such as grounding yourself by touching any grounded surface before touching the card.

Hardware Installation

Make sure to set switches and jumpers from either the Option Selection section of this manual or from the suggestions of SETUP.EXE.

Do not install the card into the computer until the software has been fully installed.
Turn OFF the computer power AND unplug the AC power from the system.
Remove the computer cover.

Carefully install the card in an available 5V or 3.3V PCI expansion slot (you may need to remove a backplate first).
Inspect for proper fit of the card and tighten screws. Make sure that the card mounting bracket is properly screwed into place and that there is a positive chassis ground.
Install an I/O cable onto the card’s bracket-mounted connector.

Replace the computer cover and turn ON the computer. Enter the CMOS setup program of your system and verify that the PCI plug-and-play option is set appropriately for your system. Systems running Windows 95/98/2000/XP/2003 (or any other PNP-compliant operating system) should set the CMOS option to OS. Systems running under DOS, Windows NT, Windows 3.1, or any other non-PNP-compliant operating system should set the PNP CMOS option to BIOS or Motherboard. Save the option and continue booting the system.
Most computers should auto-detect the card (depending on the operating system) and automatically finish installing the drivers.
Run PCIfind.exe to complete installing the card into the registry (for Windows only) and to determine the assigned resources.

Run one of the provided sample programs that was copied to the newly created card directory (from the CD) to test and validate your installation.

Option Selection

To help you locate the jumpers described in this section, refer to the Option Selection Map at the end of this section. Operation of the serial communications section is determined by jumper installation as described in the following paragraphs.

Terminations

A transmission line should be terminated at the receiving end in its characteristic impedance. Installing a jumper at the locations labeled LDxO applies a 120Ω load across the transmit/receive input/output for RS485 operation.
In RS485 operations where there are multiple terminals, only the RS485 ports at each end of the network should have terminating impedance as described above.
To terminate the COM A port, place a jumper at the location labeled LDAO. To terminate the COM B, COM C, and COM D ports, place jumpers at locations labeled LDBO, LDCO, and LDDO, respectively.

Also, for RS485 operation, there must be a bias on the RX+ and RX- lines. If the card is not to provide that bias, contact the factory technical support.

Data Cable Wiring

Signal Pin Connection

TX+ and RX+ 2
TX- and RX- 3
Ground 5

Baud Rate Ranges

The jumpers labeled CLK X1 and CLK X4 select the baud rates in either of two ranges. When in the “X1” position, the baud rate range is up to 115,200 baud. When in the CLK X4 position, the baud rate range is up to 460,800 baud.
Note: Refer to Table 5-1, Baud Rate Divisor Table of the manual.

Interrupts

Please note that, in Windows NT, changes must be made to the system registry to support IRQ sharing.
The following is excerpted from “Controlling Multiport Serial I/O Cards” provided by Microsoft in the MSDN library, documentid:mk:@ivt:nt40res/D15/S55FC.HTM, also available in the Windows NT Resource Kit.

The Microsoft serial driver can be used to control many dumb multiport serial cards. Dumb indicates that the control includes no onboard processor. Each port of a multiport card has a separate subkey under the HKLM\CurrentControlSet\Services\Serial subkey in the registry. In each of these subkeys, you must add values for DosDevices, Interrupt, InterruptStatus, PortAddress, and PortIndex because these are not detected by the Hardware Recognizer.
(For descriptions and ranges for these values, see Regentry.hlp, the Registry help file on the Windows NT Workstation Resource Kit CD.)
For example, if you have a four-port card configured to use address 0xFFF0 with an interrupt of 05, the values in the Registry are: [assuming that every port is configured to use the same IRQ and that the addresses are configured to be consecutive and contiguous]

Serial2 Subkey:
- PortAddress = REG_DWORD 0xFFF0 Interrupt = REG_WORD 5 DosDevices = REG_SZ COM3 InterruptStatus = REG_DWORD 0xFFF8 PortIndex = REG_DWORD 1
Serial3 Subkey:
- PortAddress = REG_DWORD 0xFFE0 Interrupt = REG_DWORD 5 DosDevices = REG_SZ COM4 InterruptStatus = REG_DWORD 0xFFF8 PortIndex = REG_DWORD 2
Serial4 Subkey:
- PortAddress = REG_DWORD 0xFF90 Interrupt = REG_DWORD 5 DosDevices = REG_SZ COM5 InterruptStatus = REG_DWORD 0xFFF8 PortIndex = REG_DWORD 3

Serial5 Subkey:
- PortAddress = REG_DWORD 0xFF80 Interrupt = REG_DWORD 5 Dos Devices = REG_SZ COM6 InterruptStatus = REG_DWORD 0xFFF8 PortIndex = REG_DWORD 4
As this example shows, the Interrupt Status Register, which indicates which port (s) caused an IRQ, is located at COM A Base Address +8.

Address Selection

The card uses four separate address spaces. COM A occupies 16 consecutive register locations, and COM B, COM C, and COM D each occupy eight consecutive register locations.
PCI architecture is Plug-and-Play. This means that the BIOS or Operating System determines the resources assigned to PCI cards rather than you selecting those resources with switches or jumpers. As a result, you cannot set or change the card’s base address.
You can only determine what the system has assigned.

To determine the base address that has been assigned, run the PCIFind.EXE utility program provided.
This utility will display a list of all of the cards detected on the PCI bus, the addresses assigned to each function on each of the cards, and the respective IRQs (if any) allotted.
Alternatively, some operating systems (Windows 95/98/2000) can be queried to determine which resources were assigned. In these operating systems, you can use either PCIFind (DOS), PCINT (Windows 95/98/NT), or the Device Manager utility from the

System Properties Applet of the Control Panel. The card is installed in the Data Acquisition class of the Device Manager list. Selecting the card, clicking Properties, and then selecting the Resources Tab will display a list of the resources allocated to the card.
PCIFind uses the Vendor ID and Device ID to search for your card, then reads the base address and IRQ.
If you want to determine the base address and IRQ yourself, use the following information.
The Vendor ID for the card is 494F. (ASCII for “IO”)
The Device ID for the card is 1059h.

Programming

Sample Programs

There are sample programs provided with the card in C, Pascal, QuickBASIC, and several Windows languages. DOS samples are located in the DOS directory, and Windows samples are located in the WIN32 directory.

Windows Programming

The card installs into Windows as a COM port. Thus, the Windows standard API functions can be used.

In particular:

► CreateFile() and CloseHandle() for opening and closing a port.
► SetupComm(), SetCommTimeouts(), GetCommState(), and SetCommState() to set and change a port’s settings.
► ReadFile() and WriteFile() for accessing a port.
See the documentation for your chosen language for details.
Under DOS, the process is very different. The remainder of this chapter describes DOS programming.

Initialization

Initializing the chip requires knowledge of the UART’s register set. The first step is to set the baud rate divisor. You do this by first setting the DLAB (Divisor Latch Access Bit) high.
This bit is Bit 7 at Base Address +3. In C code, the call would be: outportb(BASEADDR +3,0×80);
You then load the divisor into Base Address +0 (low byte) and Base Address +1 (high byte). The following equation defines the relationship between baud rate and divisor: desired baud rate = (UART Clock Frequency) / (32 * divisor)
On the card, the UART clock frequency is 1.8432 MHz. Below is a table for the popular divisor frequencies.
When the BAUD jumper is in the X1 position, the UART clock frequency is 1.8432 MHz. When the jumper is in the X4 position, the clock frequency is 7.3728 MHz.
The following table lists popular divisor frequencies. Note that there are two columns to consider depending on the position of the BAUD jumper.

Baud Rate	Divisor x1	Divisor x4	Max Diff. Cable Length*
460800	–	1	550 ft
230400	–	2	1400 ft
153600	–	3	2500 ft
115200	1	4	3000 ft
57600	2	8	4000 ft
38400	3	12	4000 ft
28800	4	16	4000 ft
19200	6	24	4000 ft
14400	8	32	4000 ft
9600	12	48 – Most Common	4000 ft
4800	24	96	4000 ft
2400	48	192	4000 ft
1200	96	384	4000 ft

Recommended maximum distances for differentially driven data cables (RS-422 or RS485) are for typical conditions.

Table 5-1: Baud Rate Divisors

In C, the code to set the chip to 9600 baud is.
outportb(BASEADDR, 0x0C);
outportb(BASEADDR +1,0);

In C, the code to set the chip to 9600 baud is:

outportb(BASEADDR, 0x0C);
outportb(BASEADDR +1,0);
The second initializing step is to set the Line Control Register at Base Address +3. This register defines word length, stop bits, parity, and the DLAB.
Bits 0 and 1 control word length and allow word lengths from 5 to 8 bits. Bit settings are extracted by subtracting 5 from the desired word length.
Bit 2 determines the number of stop bits. There can be either one or two stop bits. If Bit 2 is set to 0, there will be one stop bit. If Bit 2 is set to 1, there will be two stop bits.
Bits 3 through 6 control parity and break enable. They are not commonly used for communications and should be set to zeroes.
Bit 7 is the DLAB discussed earlier. It must be set to zero after the divisor is loaded, or else there will be no communications.
The C command to set the UART for an 8-bit word, no parity, and one stop bit is: outportb(BASEADDR +3, 0x03)
The final initialization step is to flush the receiver buffers. You do this with two reads from the receiver buffer at Base Address +0. When done, the UART is ready to use.

Reception

Reception can be handled in two ways: polling and interrupt-driven. When polling, reception is accomplished by constantly reading the Line Status Register at Base Address +5. Bit 0 of this register is set high whenever data is ready to be read from the chip.
A simple polling loop must continuously check this bit and read in data as it becomes available. The following code fragment implements a polling loop and uses a value of 13 (ASCII Carriage Return) as an end-of-transmission marker.

{ while (!(inportb(BASEADDR +5) & 1)); /*Wait until data ready*/ data[i++]= inportb(BASEADDR);}
while (data[i]!=13); /*Reads the line until null character rec’d*/
Interrupt-driven communications should be used whenever possible and are required for high data rates.
Writing an interrupt-driven receiver is not much more complex than writing a polled receiver, but care should be taken when installing or removing your interrupt handler to avoid writing the wrong interrupt, disabling the wrong interrupt, or turning interrupts off for too long a period.
The handler would first read the Interrupt Identification Register at Base Address +2. If the interrupt is for Received Data Available, the handler then reads the data. If no interrupt is pending, control exits the routine.
A sample handler, written in C, is as follows: readback = importb (BASEADDR +2); if (readback & 4) /*Readback will be set to 4 if data is available*/ data[i++]=inportb(BASEADDR); outportb(0x20,0x20); /*Write EOI to 8259 Interrupt Controller*/ return;

Transmission

RS485 transmission is simple to implement. The AUTO feature of the card automatically enables the transmitter when data is ready to send, so no software enabling is required. The following software example is for non-AUTO operation.
To transmit a string of data, the transmitter must first check Bit 5 of the Line Status Register at Base Address +5. That bit is the transmitter-holding-register-empty flag.
If it is high, the transmitter has sent the data. The process of checking the bit until it goes high, followed by a write, is repeated until no data remains.
The following C code fragment demonstrates this process: outportb(BASEADDR +4, inportb(BASEADDR +4)|0x02); /*Set RTS bit without altering states of other bits*/ while(data[i]); /*While there is data to send*/
{ while(!(inportb(BASEADDR +5)&0x20)); /*Wait until transmitter is empty*/ outportb(BASEADDR,data[i]); i++; } outportb(BASEADDR +4, inportb(BASEADDR +4)&0xFD); /*Reset RTS bit without altering states of other bits*/

Connector Pin Assignments

The popular 9-pin D subminiature connector is used for interfacing to communication lines. The connector is equipped with 4-40 threaded standoffs (female screw lock) to provide strain relief.

Table 6-1: Connector Pin Assignments

Pin No.	RS485 Functions
1
2	Tx+ and Rx+
3	Tx- and Rx-
4
5	GND Ground
6
7
8
9

Appendix A: Application Considerations

Introduction

Working with RS-422 and RS485 devices is not much different from working with standard RS-232 serial devices, and these two standards overcome deficiencies in the RS-232 standard.
First, the cable length between two RS232 devices must be short, less than 50 feet at 9600 baud. Second, many RS232 errors are the result of noise induced on the cables.
The RS-422 standard permits cable lengths up to 5000 feet and, because it operates in the differential mode, it is more immune to induced noise.

Connections between two RS-422 devices (with CTS ignored) should be as follows:

Device #1		Device #2
Signal	Pin No.	Signal	Pin No.
Gnd	7	Gnd	7
TX⁺	24	RX⁺	12
TX^–	25	RX^–	13
RX⁺	12	TX⁺	24
RX^–	13	TX^–	25

Table A-1: Connections Between Two RS422 Devices

A third deficiency of RS232 is that more than two devices cannot share the same cable. This is also true for RS-422, but RS485 offers all the benefits of RS-422, plus allows up to 32 devices to share the same twisted pairs.
An exception to the foregoing is that multiple RS-422 devices can share a single cable if only one will talk and the others will all receive.

Balanced Differential Signals

The reason that RS-422 and RS485 devices can drive longer lines with more noise immunity than RS-232 devices is that a balanced differential drive method is used. In a balanced differential system, the voltage produced by the driver appears across a pair of wires. A balanced line driver will produce a differential voltage from +2 to +6 volts across its output terminals. A balanced line driver can also have an input “enable” signal that connects the driver to its output terminals. If the “enable signal is OFF, the driver is disconnected from the transmission line. This disconnected or disabled condition is usually referred to as the “tristate” condition and represents a high impedance. RS485 drivers must have this control capability.
RS-422 drivers may have this control, but it is not always required.
A balanced differential line receiver senses the voltage state of the transmission line across the two signal input lines. If the differential input voltage is greater than +200 mV, the receiver will provide a specific logic state on its output.
If the differential voltage input is less than -200 mV, the receiver will provide the opposite logic state on its output. The maximum operating voltage range is from +6V to —-6V, allowing for voltage attenuation that can occur on long transmission cables.
A maximum common mode voltage rating of +7V provides good noise immunity from voltages induced on the twisted pair lines. The signal ground line connection is necessary to keep the common mode voltage within that range.
The circuit may operate without the ground connection, but it might not be reliable.

Parameter	Conditions	Min.	Max.
Driver Output Voltage (unloaded)		4V	6V
		-4V	-6V
Driver Output Voltage (loaded)	LD and LDGND	2V
	jumpers in	-2V
Driver Output Resistance			50Ω
Driver Output Short-Circuit Current			+150 mA
Driver Output Rise Time			10% unit interval
Receiver Sensitivity			+200 mV
Receiver Common Mode Voltage Range			+7V
Receiver Input Resistance			4KΩ

Table A-2: RS422 Specification Summary

To prevent signal reflections in the cable and to improve noise rejection in both the RS-422 and RS485 modes, the end of the cable should be terminated with a resistance equal to the characteristic impedance of the cable.
(An exception to this is the case where the line is driven by an RS422 driver that is never “tristated” or disconnected from the line. In this case, the driver provides a low internal impedance that terminates the line at that end.)

Note

You do not have to add a terminator resistor to your cables when you use the card.
Termination resistors for the Tx+/Rx+ and Tx-/Rx- lines are provided on the card and are placed in the circuit when you install the LD jumpers. (See the Option Selection section of this manual.)

RS485 Data Transmission

The RS-485 standard allows a balanced transmission line to be shared in a party-line mode. As many as 32 driver/receiver pairs can share a two-wire party line network. Many characteristics of the drivers and receivers are the same as in the RS-422 Standard.
One difference is that the common mode voltage limit is extended and is +12V to 7V. Since any driver can be disconnected (or tristated) from the line, it must withstand this common mode voltage range while in the tristate condition.
The following illustration shows a typical multidrop or party line network. Note that the transmission line is terminated on both ends of the line but not at drop points in the middle of the line.

RS485 Four-Wire Multidrop Network

An RS485 network can also be connected in a four-wire mode. In a four-wire network, it’s necessary that one node be a master node and all others be slaves.
The network is connected so that the master communicates to all slaves, and all slaves communicate only with the master.
This has advantages in equipment that uses mixed protocol communications. Since the slave nodes never listen to another slave’s response to the master, a slave node cannot reply incorrectly.

Customer Comments

If you experience any problems with this manual or just want to give us some feedback, please email us at: manuals@accesio.com.
Please detail any errors you find and include your mailing address so that we can send you any manual updates.
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Tel. 8585509559
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Assured Systems

Assured Systems is a leading technology company with over 1,500 regular clients in 80 countries, deploying over 85,000 systems to a diverse customer base in 12 years of business.
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Frequently Asked Questions

Q: What is the warranty coverage for the PCI-COM485/4?
- A: The warranty covers repairs and replacements for the first three years from the date of shipment. After that period, on-site or in-plant service is available at reasonable rates.
Q: How many serial ports are available on the PCI-COM485/4?
- A: The PCI-COM485/4 model provides four serial ports for connecting external devices.

Documents / Resources

ASSURED PCI-COM485-4 Official ACCES I O Distributor and Integrator [pdf] User Manual
PCI-COM485-4, PCI-COM485-4 Official ACCES I O Distributor and Integrator, PCI-COM485-4, Official ACCES I O Distributor and Integrator, ACCES I O Distributor and Integrator, Distributor and Integrator, Integrator

References

User Manual

ASSURED PCI-COM485-4 Official ACCES I/O Distributor and Integrator

Product Usage Instructions