Chapter 3: Power & Communication Configuration Chapter 3 ● Power & Communication Configuration This chapter describes the electrical options, power requirements and communication configuration of the HF-0405 Series RFID Controller. Power Requirements To function properly, the HF-0405 must be powered by a power supply capable of providing voltages of 10 to 30 volts DC, with an Operating Range of 180mA and a Surge Current of 250mA. Refer to Appendix B for power supplies offered by Escort Memory Systems.
Chapter 3: Power & Communication Configuration Serial Interface Options There are three distinct versions of the HF-0405 RFID Controller. Each version provides supports for one specific serial interface requirement. Prior to purchasing one or more HF-0405 Series RFID Controllers, determine which of the three serial interface protocols your Host and RFID application will require.
Chapter 3: Power & Communication Configuration RS232 Interface Connection In a point-to-point configuration where the distance from the Host to the HF-0405 is less than 15 meters, it is possible to connect the two through an RS232 serial interface connection. The recommended cable medium for RS232 communication is produced by Belden, part number 9941. This cable is non-paired, 22 AWG stranded (7x30) tinned copper with S-R PVC insulation. Specifications for Belden cables can be found at WWW.BELDEN.COM.
Chapter 3: Power & Communication Configuration Making Connections Connect the HF-0405 to the appropriate serial interface on the Host: RS232, RS422 or RS485. Connecting the HF-0405 to the Host 1. Connect the female end of your M12 serial communications cable to the male plug on the HF-0405. 2. Connect the other end of the serial communications cable to your Host’s COM1 port (RS232 or RS422 compatible). 3. Note COM1 default settings of 9600 baud, 8 data bits, 1 stop bit, no parity, and no flow control.
Chapter 3: Power & Communication Configuration Pinouts HF-0405-232/422 Pinouts RS232 - Pin Descriptions RS422 - Pin Descriptions 1. 24V DC PWR 1. 24V DC PWR 2. 0V (Power GND) 2. 0V (Power GND) 3. N.C. 3. TX+ 4. N.C. 4. TX- 5. N.C. 5. RX+ 6. RX 6. RX- 7. TX 7. TX232 8. Shield (Communication GND) 8. Shield (Communication GND) N.C.
Chapter 3: Power & Communication Configuration HF-0405-485 Pinouts RS485 - Pin Descriptions 1. Shield (Communication GND) 2. 24V DC PWR 3. 0V (Power GND) 4. TX/RX+ 5.
Chapter 3: Power & Communication Configuration The Configuration Tag Configuration Tag Overview In the past, RFID controllers had multiple jumpers and dip switches which were used to set configuration parameters. The HF-0405 Controllers have no switches and are software configurable via commands. In the event that serial communication parameters are improperly assigned, recycle power to the RFID controller and place the configuration card in the RF field.
Chapter 4: LED Status Chapter 4 ● LED Status This chapter describes the functions of the LEDs on the HF-0405 and explains their error condition messages. The HF-0405 Series RFID Controllers have eight LEDs. The LEDs are conveniently located on the top panel of the HF-0405 and display everything from RF and COM activity to tag presence, diagnostic information and power status.
Chapter 4: LED Status LED Descriptions RF LED, Color is Red: the RF LED will turn on when RF power is being transmitted from the antenna and stays on during entire RF operation. By default, this occurs each time an RF command is being executed. COM LED, Color is Green: the COM LED indicates that data is being sent or received. On receipt of a command, the COM LED will begin flashing on and off rapidly. After the controller issues the command response, the COM LED flashing will halt.
Chapter 4: LED Status HF-0405-232 LED Status On the HF-0405-232 model, the yellow LED 20 should be on steady state to indicate RS232 mode. 4 2 3 2 2 2 1 2 0 PWR COM RF 2 RF Field HF-0405-422 LED Status On the HF-0405-422 model, the yellow LED 21 should be on steady state to indicate RS422 model.
Chapter 4: LED Status HF-0405-485 LED Status The five yellow LEDs on the HF-0405-485 indicate Subnet16 node address (used in conjunction with Escort Memory Systems’ Subnet16 Gateway or Subnet16 Hub). Weighted by powers of 2, the yellow LEDs indicate (in binary) the current Subnet16 node address assigned to the HF-0405-485. For example: 20 = 0x01 (node 1), 21 = 0x02 (node 2), 22 = 0x04 (node 4), 23 = 0x08 (node 8), 24 = 0x10 (node 16). There are 16 functional Subnet16 node addresses (1 – 16).
Chapter 4: LED Status Node 9 4 3 2 1 0 R C 2 2 2 2 2 P F O W M R Node 12 4 3 2 1 0 R C 2 2 2 2 2 P F O W M R Node 15 4 3 2 1 0 R C 2 2 2 2 2 P F O W M R Node 10 4 3 2 1 0 R C 2 2 2 2 2 P F O W M R Node 13 4 3 2 1 0 R C 2 2 2 2 2 P F O W M R Node 11 4 3 2 1 0 R C 2 2 2 2 2 P F O W M R Node 14 4 3 2 1 0 R C 2 2 2 2 2 P F O W M R Node 16 4 3 2 1 0 R C 2 2 2 2 2 P F O W M R 43
Chapter 4: LED Status Special LED Operation Functions Updating Firmware (Part 1) With the PWR LED on the right, the LEDs will illuminate one at a time sequentially from right to left to indicate that the firmware update file is being copied to internal memory. The LEDs will repeat this R to L sequence until the controller has completely received the firmware update file.
Chapter 4: LED Status Updating Firmware (Part 2) After the update file has been copied to internal memory, the LEDs will blink on and off repeatedly during which time the update file is being written to flash memory. Warning: do not cancel or abort this operation, do not unplug or remove power from the controller until this procedure is completed.
Chapter 4: LED Status Error Conditions When an RFID operation error occurs, other than a Command Timeout, the red RF LED and one or more yellow LEDs will flash in unison. The yellow LEDs represent the error code in binary. The COM LED will stay on to help orient the binary LED positions. The yellow LEDs will continue to flash the error code until a valid command is received. If an unrecoverable error occurs, the LEDs will continuously flash the error code until the controller has been reset.
Chapter 5: Communication Protocols Chapter 5 ● Communication Protocols This chapter contains an overview of the protocols used by the HF-0405 to communicate with the Host and describes how to use them to issue RFID commands. Communication Overview When an RFID command is issued, the Host computer instructs the RFID controller to perform a given task.
Chapter 5: Communication Protocols option is chosen for its ease of use. However, we encourage the use of checksums for most applications. ABx Command Structures In its simplest form, ABx commands are comprised of a header, a number of parameters, and a command terminator. The structure of every ABx command will, at the very least, contain these basic elements.
Chapter 5: Communication Protocols ABx Command Parameters ABx commands have specific parameters that may be modified depending on your application. Some of the typical Command Parameters include: Command Size, Packet Length, Command Timeout and Starting Address. Command Timeout Most ABx commands require the setting of a Timeout Value that is used to limit the length of time that the HF-0405 will attempt to complete a specified operation.
Chapter 5: Communication Protocols Checksum Options ABx Fast and ABx ASCII commands permit the use of an optional checksum byte. Checksums are used to verify the integrity of the data being transmitted. To enable the use of a checksum value, use the RFID Demonstration Utility and select ABx Fast with Checksum or ABx ASCII with Checksum when starting the program.
Chapter 5: Communication Protocols ABx Fast Command Protocol The default command protocol used by the HF-0405 is ABx Fast (Without Checksum). This protocol differs from ABx Standard in that the smallest addressable data element is one byte, rather than the 2-byte “word” structure of ABx Standard. However, ABx Fast commands and responses do contain two-byte words that indicate the size and length of various Command Parameters. ABx Fast also supports the use of a one-byte optional Checksum.
Chapter 5: Communication Protocols ABx Fast – Response Packet Structure Field Header Response Size Command ID Start Address Read / Write Address Length Timeout Data Value Byte Checksum Terminator Content 0x0202 2-byte value indicating packet length in bytes excluding header, command size, checksum and terminator. 1-byte value for Command ID Number 2-byte value to identify the read/write starting address. 2-byte value to identify the number of addresses to be read or written to.
Chapter 5: Communication Protocols ABx ASCII Command Protocol The ABx ASCII command protocol is based on the ABx Fast command protocol, however, ABx ASCII goes one step further by converting command hex values into printable ASCII characters. In another words, hex values displayed in an ABx Fast command are transmitted as separate ASCII characters in ABx ASCII.
Chapter 5: Communication Protocols ABx ASCII - Command Packet Structure The ABX ASCII protocol is based on the following minimal command packet structure. Depending on the command issued and your Checksum setting, the Data Byte and Checksum fields may not be present.
Chapter 5: Communication Protocols ABx ASCII - Command Example ABx ASCII Command 04 – Tag Fill Example In this example, the RFID controller is directed to fill a number of address locations with a specific data value byte, beginning at a specified starting address location. When Block Size = 0, the HF-0405 will fill the tag until it reaches the end of available memory. This command is similar to the ABx Fast version of the command.
Chapter 5: Communication Protocols ABx ASCII - Response Structure After a successful operation, the controller will send back a response. The response may not include the Data Byte Value or Checksum fields (depending on the Command ID and your Checksum settings). However, if a Checksum is enabled, it will always be returned in the Command Response.
Chapter 5: Communication Protocols ABx ASCII Error Response Example A block write fail error response might appear as the following ASCII character string: Code sample: 0006FF0643 However, in Hex, the same error response would appear as: Code Sample: 0x02 0x02 0x30 0x30 0x03 0x32 0x46 0x46 0x30 0x36 0x46 0x38 0x03 57
Chapter 5: Communication Protocols ABx Standard Command Protocol ABx Standard is a binary, 2-byte, word oriented protocol where data is transmitted in 2-byte increments, the Most Significant Byte (MSB) and the Least Significant Byte (LSB). In a serial transmission, the MSB is transmitted first. Note that the MSB is sometimes called the High Byte and the LSB is sometimes called the Low Byte.
Chapter 5: Communication Protocols ABx Standard - Command Packet Structure Field Header Command ID Start Address Address Length in Bytes Timeout Data Value Byte Terminator Number of Bytes 1 1 2 2 2 2 2 Content 0xAA is always the MSB of the first word of an ABx Standard command. The Command ID is always the LSB of the first word. 2-byte value for the address of the first byte of tag memory to be accessed. 2-byte value indicating the number of contiguous bytes to be accessed.
Chapter 6: RFID Commands Chapter 6 ● RFID Commands For the most part, RFID commands can be divided into two primary categories: 1. Controller Operation Commands Controller Operation Commands are used to manually set or modify the HF0405’s internal configuration. 2. Tag Operation Commands Tag Operation Commands require the presence of an RFID tag in the RF field and can be further sub-divided into Read and Write commands.
Chapter 6: RFID Commands Command 04 ◘ (0x04): Tag Fill DESCRIPTION Fill an RFID tag with a one byte value over multiple contiguous addresses. DISCUSSION This command is commonly used to clear contiguous segments of a tag's memory. It writes a one byte value repeatedly across a specified range of tag addresses. The fill function requires one data value byte, a starting address, and a fill length.
Chapter 6: RFID Commands Response from Controller Field Header Response Size Command Echo Checksum Terminator Content 0x0202 2-byte value indicating response packet length in bytes excluding header, response size, checksum and terminator Command ID number in Hex (0x04) Optional Checksum 0x03 Command 04 (Fill Tag) - ABx Fast Command Example This example instructs the HF-0405 to write the ASCII character 'A' (0x41) to the entire tag starting at address 0x0000.
Chapter 6: RFID Commands Command 04 (Fill Tag) – ABx Standard Command Structure Field Command Start Address Fill Length Timeout Data Value Byte Terminator Content 0xAA followed by Command ID number in Hex (0x04).
Chapter 6: RFID Commands Command 05 ◘ (0x05): Read Data DESCRIPTION Read data from contiguous (sequential) areas of the RFID tag's read/write memory. DISCUSSION The Read Data command is used to read bytes from contiguous areas of tag memory. This command consists of the Header and Command ID number, a Start Address and Read Length, followed by the message Terminator. The minimum read length is 1 byte. The maximum is the entire read/write address space of the tag.
Chapter 6: RFID Commands Command 05 (Read Data) - ABx Fast Command Example This example instructs the controller to read 4 bytes of data from the tag starting at address 0x0000. A timeout of 2 seconds (0x07D0 = 2000 x 1 msecs increments) is set for the completion of the Read Data command.
Chapter 6: RFID Commands Command 05 (Read Data) - ABx Standard Command Structure Field Header & Command ID Start Address Read Length Timeout Terminator Content 0xAA followed by Command ID number in Hex (0x05) 2-byte value for tag address where the fill will start 2-byte value for the number of bytes to be read Timeout value measured in 1 msec units (0x001E – 0xFFFE) 0xFFFF Command 05 (Read Data) - ABx Standard Command Example The goal of this example is to read 10 bytes of data from the tag sta
Chapter 6: RFID Commands Command 06 ◘ (0x06): Write Data DESCRIPTION Write data to an RFID tag. DISCUSSION This command is used to write segments of data to contiguous addresses of tag memory. It is capable of transferring up to 100 bytes of data from the Host with one command. The Write Data command consists of a header, the Command ID, the Start Address of the Write, followed by the data value stream to be written to the RFID tag.
Chapter 6: RFID Commands Command 06 (Write Data) – ABx Fast Command Example This example writes 4 Bytes of data to the tag starting at address 0x0000. A timeout of 2 seconds (0x07D0 = 2000 x 1 msec increments) is set for the completion of the Block Write.
Chapter 6: RFID Commands Command 06 (Write Data) – ABx Standard Command Structure For ABx Standard, data to be written to the tag is contained in the LSB of the Data Byte Value, and the MSB is always 0x00.
Chapter 6: RFID Commands Command 07 ◘ (0x07): Read Tag ID (SN) DESCRIPTION This command retrieves the eight-byte tag ID or serial number. DISCUSSION Each ISO 14443 and ISO 15693 compliant tag has a unique 8 byte ID or serial number. By using just eight bytes, manufacturers can generate over 280 trillion possible serial numbers. Once a tag is given an ID or serial number it can not be changed and is not part of the available read/write address space of a tag.
Chapter 6: RFID Commands Command 07 (Read Tag ID) – ABx Fast Command Example This example will wait until a tag is in range and then reads the 8-byte ID or serial number. In this example the serial number is F2720300000104E0.
Chapter 6: RFID Commands Command 07 (Read Tag ID) – ABx Standard Command Structure When running this command, the tag ID or serial number is returned in the LSB only, with 0x00 as the MSB.
Chapter 6: RFID Commands Command 08 ◘ (0x08): Tag Search DESCRIPTION This command instructs the RFID Controller to search for a tag in the RF field. DISCUSSION This command will instruct the controller to search for the presence of a tag within range of the antenna. If the controller finds a tag it will return a command echo to the host. The timeout value is measured in 1 msec increments and can have a value of 0x001E to 0xFFFE (30 to 65,534 msecs).
Chapter 6: RFID Commands Command 08 (Tag Search) – ABx Fast Command Example This example checks for any RFID tag within range of the antenna. A timeout of 2 seconds (0x07D0 = 2000 msecs) is set for the completion of the Tag Search.
Chapter 6: RFID Commands Command 08 (Tag Search) – ABx Standard Command Structure Field Header & Command ID Timeout Value Terminator Content 0xAA followed by Command ID number in Hex (0x08) Timeout value measured in 1 msec units (0x0001 – 0xFFFE) 0xFF 0xFF Command 08 (Tag Search) – ABx Standard Command Example This example has the RFID Controller check for a tag in the RF field. A timeout of 2 seconds (0x07D0) is set for the completion of the Tag Search.
Chapter 6: RFID Commands Command 0D Read ◘ (0x0D): Start/Stop Continuous DESCRIPTION This command instructs the controller to start (or stop) Continuous Read mode. DISCUSSION The Start/Stop Continuous Read command contains three parameters: • Start Address • Read Length • Delay Between Duplicate Decodes When the HF-0405 is in Continuous Read Mode, it will constantly emit RF energy in an attempt to read any tag that comes into range of the antenna.
Chapter 6: RFID Commands Continuous Read Mode LED Behavior LED Behavior Description PWR ON The controller is powered and functioning. COM BLINKING A tag has entered the RF field. RF ON A tag has been read and is still in the field. RF OFF A previously read tag has been out of range for the specified time.
Chapter 6: RFID Commands Command 0D (Start/Stop Continuous Read) – ABx Fast Command Example This example places the controller in Continuous Read mode and reads 8 Bytes of data from the tag starting at address 0x0001. A delay between identical reads of 2 seconds (0x0002 = 2 x 1 second increments) is set.
Chapter 6: RFID Commands Command 0D (Start/Stop Continuous Read) – ABx Standard Command Structure Field Header & Command ID Start Address Read Length Delay Between Identical Decodes Terminator Content 0xAA followed by Command ID number in Hex (0x0D) 2 byte value for the start address of the read 2 byte value for the number of bytes to be read. Time the tag must be out of RF field before controller will transmit data again from same tag. Value is expressed in 1 second units.
Chapter 6: RFID Commands Response from Controller The controller will first return an acknowledgment of the command followed by a response containing read data when a tag enters the antenna field.
Chapter 6: RFID Commands Response from Controller Field Content Command Echo Terminator (MSB/LSB) (MSB/LSB) 0xAA 0x0D 0xFF 0xFF Code Sample: AA 0D FF FF 81
Chapter 6: RFID Commands Command 0A ◘ (0x0A): Set RS232/422 Baud Rate DESCRIPTION This command controls the Baud Rate of the serial communications protocol for Serial Port COM 1. DISCUSSION This command is used to change the Baud Rate from the default of 9600bps. After this command has been initiated, communications with the RFID Controller will cease until the Host has re-established communications at the new rate. The following baud rates can be set using the corresponding hex value in the command.
Chapter 6: RFID Commands Command 0A (Set Baud Rate) – Command Example This example changes the baud rate to 19200.
Chapter 6: RFID Commands ◘ (0x36): Send Controller Command 36 Configuration Use the RFID Demonstration Utility to run Commands 36, 37, 38 and A1. The RFID Demonstration Utility can be downloaded from: http://www.ems-rfid.com/hf-series.html. After installing and starting the utility, click COMMAND and select 36H from the drop down menu.
Chapter 6: RFID Commands The following configuration box will appear. At this screen you can change the following settings: • Tag Type • Command Protocol • Baud Rate When you are done making changes click “SEND SETTINGS”. The new settings will be sent to the HF-0405 controller.
Chapter 6: RFID Commands ◘ (0x37): Read Controller Command 37 Configuration Use the RFID Demonstration Utility to run Command 37. After starting the utility, click COMMAND and select 37H from the drop down menu.
Chapter 6: RFID Commands The following configuration box will appear. At this screen click “UPLOAD SETTINGS”. The current settings from the controller will be uploaded to the RFID Demonstration Utility.
Chapter 6: RFID Commands Command 38 ◘ (0x38): Read Controller SN Use the RFID Demonstration Utility to run Command 38. This command is used to read the RFID Controller hardware serial number. After starting the utility, click COMMAND and select 38H from the drop down menu. The RFID Demonstration Utility will return information similar to the following: Read reader/writers information response: Reader/writer type: Version: 1 0.0T.
Chapter 6: RFID Commands RC632 internal: RC632 RsMaxP: B669 65 RC632 Information CRC: A6 Command Code Sample: 02 02 00 01 38 03 Response Code Sample: 02 02 00 1B 38 01 00 00 54 05 01 98 6E 98 6E 30 FF FF 0F 04 00 00 00 05 E1 96 44 B6 69 65 A6 03 89
Chapter 6: RFID Commands Command A1 ◘ (0xA1): Reset Controller Use the RFID Demonstration Utility to run Command A1. This command is used to reset the RFID Controller. After starting the utility, click COMMAND and select A1H from the drop down menu. The controller will be reset to factory default settings.
Chapter 7: ABx Error Codes Chapter 7 ● ABx Error Codes The RFID controller will return an error code (in Hex) if it encounters a fault during operation. ABx errors are caused, primarily by improperly entering command parameter syntax. Entering an incorrect length value, for example, will generate an error. If the controller is powered down and looses its internal configuration, simply executing any command could generate errors.
Chapter 7: ABx Error Codes ABx Fast Error Response Structure The structure of an ABx Fast error response is shown below (where XX is a 1-byte value indicating the error that occurred).
Chapter 7: ABx Error Codes ABx ASCII Error Response Structure The Structure of an ABx ASCII error response is shown below.
Chapter 7: ABx Error Codes ABx Standard Error Response Structure The Structure of the ABx Standard error response from the RFID Controller is shown below.
Chapter 8: Troubleshooting Chapter 8 ● Troubleshooting This chapter is designed to help if you are having difficulties using the HF-0405. HF-0405 Troubleshooting Table Problem Symptom Possible Reason Resolution Controller LEDs not functioning Check power Unable to read tag Check proximity to controller, Try different tag Etc. Etc. Contact Technical Support Hours of Operation 7am-5pm PST Escort Memory Systems Technical Support Department 170 Technology Circle Scotts Valley, CA 95066 U.S.
Appendix A: Specifications Appendix A ● Specifications HF-0405 Data Sheet • Low Cost 13.
Appendix A: Specifications Technical Specifications • Read/Write Range Up To: 100mm (ISO 15693) / 50mm (ISO 14433) with ISO Card Tags • Supply Voltage: 12-24VDC ±10%; 150mA@24VDC (3.60W) • 26.5kBaud/106kBaud Air Protocols with CRC Error Detection • RS232/RS422 Baud Rates: 9600, 19.2k, 38.4k, 57.6k, 115.2k • RS485 Baud Rate: 9600 or 115.
Appendix C: ASCII Chart Appendix B ● Models and Accessories HF-0405-232-01 Stock Code Quantity 00-3000 20-1940 20-5918 1.00 2.00 2.00 14-3137 1.00 Description Configuration Tag for HF-0405-232 ICODE SLI,54MM X 86MM Screw, (M4-20 PPH SS 18-8\302) Hex Nut, (M4 SS 18-8\302) Mounting Bracket for HF-0405, NORYL, BLACK GTX830 HF-0405-422-01 Stock Code Quantity 00-3001 20-1940 20-5918 1.00 2.00 2.00 14-3137 1.
Appendix C: ASCII Chart HF-0405 Compatible Accessories Tags Escort Memory Systems designs and manufactures several lines of RFID tags and transponders. In particular, the LRP and HMS series passive read/write RFID tags perform well with HF-0405 controllers. Our HMS tags are tuned slightly off frequency which improves the inductive coupling characteristics of the tag. Cables RS485 cables, connectors, Subnet16, Trunk line and Drop-T parts and accessories are available.
Appendix C: ASCII Chart Appendix C ● ASCII Chart 100
Appendix D: RFID Terminology & Definitions Appendix D ● RFID Terminology & Definitions TERM DEFINITION Active Tag An RF tag (transponder) which is partly or completely battery-powered. Batteries may be replaceable or sealed internally. Addressability The ability to address bits, fields, pages, files or other areas of memory in a transponder. Alignment An indication of the orientation of the transponder, relative to the controller antenna (this is sometimes referred to as the coupling).
Appendix D: RFID Terminology & Definitions TERM DEFINITION Binary Coded Decimal A number in binary code always written in groups of four bits, each group representing one digit of the number, for example 0011 1001 is 39. Byte Eight bits of data (0x00 01 02 03 04 05 06 07) Capacity A measure of the maximum amount of information that can be stored in a transponder. The amount may be a few bits or bytes assessable to the user, or may include addresses reserved to the manufacturer.
Appendix D: RFID Terminology & Definitions TERM DEFINITION Frequency The number of times a signal executes a complete excursion through its maximum and minimum values and returns to the same value (cycles). • LF Low Frequency 30 kHz to 300 kHz • MF Medium Frequency 300 kHz to 3 MHz • HF High Frequency 3 MHz to 30 MHz • VHF Very High Frequency 30 MHz to 300 MHz • UHF Ultra High frequency 300 MHz to 3 GHz Handshaking A mechanism for the regulation of the flow of data between devices.
Appendix D: RFID Terminology & Definitions TERM DEFINITION Memory Card A Read/Write or re-programmable transponder in credit card size. Data can be accessed via direct contact, through a microprocessor (smart card) or via a non-contact RF link. MSB Most Significant Byte. Also referred to as the High Byte or first byte in a 2-byte “word.” Multidrop Multiple devices at various locations connected in parallel (or acting similar to parallel devices).
Appendix D: RFID Terminology & Definitions TERM DEFINITION Polar Field A graphical representation of the RF field strength of a transmitting antenna. Protocol A set of rules governing the flow of information in a communications system. Range The distance between the antenna and a tag or transponder in an RFID system at which signals can be properly received. Read The action of obtaining information contained in a tag.
Appendix D: RFID Terminology & Definitions TERM DEFINITION RS422 A balanced connection interface standard similar to RS232, but using differential voltages across twisted pair wires. RS422 is more noise immune that RS232 and can be used to connect single or multiple devices to a master unit, at distances up to 3000 meters. RS485 An enhanced version of RS422, which permits multiple devices (commonly up to 32) to be attached to a twisted pair wire bus at distances of over a kilometer.
Index Index 1 13.56 MHZ ......................................................................................................................................................... See C configuration tag.................................................................................................................................................. 44 D dimensions ...................................................................................................................................................
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