User Manual
Contents
1. ee mae gad ee eee eet 14 64 1 a Tx switch off Delay long 11 bit cee eda ed de becends 15 6 4 2 b Tx switch off Delay medium 6 bit 15 643 Txewites off Delay short 3 bit gt ociosa re 15 G5 Cabling lt lt soona pa sa ee O AR A 15 651 d Tal ESTELA a a 16 6 5 2 e Half Duplex 2 wire with Echo 16 653 Hal Duplex ire mo Bebe 2 6 cee e a RA a A 16 RO Cable OPTIONS om ae Be ee Re ee ee a ee A ee ae ee 16 6 6 1 h Terminate Deli oops 25 ee a we ee ee a 16 G62 Terminate Raclines o o ia ee Pa ee ee 17 6 6 3 k Polarize Tx limes o soucs sadom SD ee ee ee ee 17 664 l Polarias Roelin s su 24 saca ee ea eR ee 17 6 7 lt Propramming Teri da eee ae eee ee ee Ba eed 17 88 U Firmware Update sekaa napa RR eH Aa A a 18 7 Proper Cabling 18 7 1 Tramemission Technique cce e 2 44 resaca ee ee ee 18 Ta SPIO 2 en a ak wwe A ewe Se Be we A ae Bee ee A Ged 19 Ta Polarization aoe Fo ee we OS Ge A eed 19 TA o ke aane E ada ee eRe Ae ee eee bee a 19 Ta A Wire DENGE cc ac RA ee ee ee a ee eo ee ao 20 8 ART and Polarization 21 8 amp 1 ART 11 bit delay ne ep somada ce au aa ew ee ee ee eS 22 8 amp 2 ART bitdelay lt c saoo aaan anm a a eee A a eS ae ae a ee 22 April 2008 SER 485 PRO SI User Manual 3 List of Tables 3 ART 2 it delay lt e aca2. option Some options are useless when certain configurations are selected in above parameters For example RS422 mode is a 4 wire operation by definition and Tx is never switched off So these options are hidden and the menu will look like figure 3 April 2008 SER 485 PRO SI User Manual 12 6 Configuration by Software VScom Converter SER 485 PRO SI v1 2 2 www vscom de www visionsystems de Operation Modes 1 RS 422 2 RS 485 controlled by RTS 3 RS 485 controlled by DTR 4 RS 485 controlled by ART Cable Options h Terminate Tx lines j Terminate Rx lines k Polarize Tx lines l Polarize Rx lines W Write to memory R Read from memory Enter new choice Figure 3 Menu Configuration as RS422 Likewise when the RS485 transceiver is controlled by the RTS or DTR signal there is no automatic switch off of the driver The delay is not offered for configuration Once the configuration is done it shall be stored by the W command To use the defined con figuration the DIP Switches shall be set to the OFF z ON setting When any DIP setting other then OFF OFF is selected the menu is closed like figure 4 VScom Converter SER 485 PRO SI v1 2 2 www vscom de www visionsystems de Operation Modes 1 RS 422 2 RS 485 controlled by RTS 3 RS 485 controlled by DTR 4 RS 485 controlled by ART Cable Options h Terminate Tx lines j Terminate Rx lines k Polarize Tx lines 1 Polariz
3. 2 wire with Echo f Half Duplex 2 wire no Echo Cable Options h Terminate Tx lines j Terminate Rx lines Polarize Tx lines 1 Polarize Rx lines W Write to memory R Read from memory Enter new choice Figure 2 Menu Factory Settings If the Terminal Emulation is not VT100 the terminal will show some funny control characters However the menu can still be read and controlled To refresh the appearance of the menu on the screen hit the lt Enter gt key You ll also notice the Enter new choice line to flicker about once per second If this annoys just hit the Space bar The top section of the menu is for the various Operation Modes available on SER 485 PRO the lower section selects details about the cabling used for communication To change the configuration punch the keys noted in the left column The menu will change and reflect the new configuration An active option is marked with an asterisk the menu is re written after each keystroke When the configuration is complete the W key will save the parameters to the non volatile memory of the SER 485 PRO The menu is still open so further changes can still be done If the configuration happens to appear as confused the latest configuration saved can be read back from the memory by the R key If no changes were done the displayed configuration is the same as the saved parameters This is noted with a sign after the W
4. 5V as low These voltages are defined against the GND signal of the transmitter The minimum differential voltage is required as 200mV by the specifications of RS422 and RS485 The receiver detects the polarity of the differential voltage and thus gets a Zero negative or a One positive To do this detection the voltages on the receivers side have to be inside the bounds of the common voltage range defined as 7V through 12V as measured against the local GND of the receiver To make sure the signals meet the common voltage range the GND of sender and receiver must be connected somehow To insure the signals are in the valid voltage range and the differential voltage can be correctly sensed by the receiver the GND lines of the transmitter and receiver April 2008 SER 485 PRO SI User Manual 18 7 Proper Cabling must be connected This is often forgotten In these cases the GND connection can be indirectly established over protective ground or over parasite ground loops which usually yield a bad GND connection For these situation the correct data receiving is not reliable or not possible 7 2 Termination When transmitted signals arrive at the end of a cable they get reflected They travel on the cable some more times which is called ringing This can cause false reading of transmitted data When the reflections travel on the cable several times they are damped and do no longer cause errors This happens earlier if the cables
5. a CR LF sequence plus the exclamation mark as prompt To receive the current configuration the software may simply send a Space char acter as command This does not change the configuration but reports the status figure 5 This example has been created by sending the characters R 4 B E J and L after receiving the prompt character 1 Enter new choice P 1 1ADhjk1 1 4ADhjk1 1 4BDhjk1 4BEhjk1 4BEh k1 4BEh k 1 Figure 5 Menu Programming Interface April 2008 SER 485 PRO SI User Manual 17 7 Proper Cabling The configuration string is seven characters long on the SER 485 PRO The first three positions just list the active options in upper case The next four positions display the status of termination and polarization in lower case the letter shows an active option otherwise a lt space gt is at that position Since this interface is for applications and not manual user input all configured options are returned This includes options not in effect as shown in 5 The options A and D have no effect since the device is in RS422 mode 1 initially The non volatile memory may be read by R and the configuration is saved by the W The software should not send control characters as commands Two commands are for manufacturing use only these are the T and the X both in upper case They have special results which may require to reset t
6. are short For long cables Termination Resistors are required These increase the damping of reflections The value of the resistor must match the impedance of the cable typically 1200 The SER 485 PRO provides an option to activate such resistors by software configuration As a rule of thumb when the cables are longer than 1000000 one million divided by the bit rate in meters you should consider Termination Resistors 7 3 Polarization In RS485 the sender must activate the transmitter before sending data and deactivate it when all data is sent At times when no devices send data all transmitters are inactive As the result the data lines are floating and the differential voltage is undefined It may happen the next data is not correctly recognized because the change from undefined to data signals is not detected To avoid such problems the data lines should be polarized by resistors These insure the differential voltage to be above 200mV Typically the positive line is pulled to 5V while the negative line is pulled to GND When Termination Resistors are applied the voltage on these must be 200mV or above The SER 485 PRO provides an option to activate such resistors by software configuration They are calculated for termination resistors of 1209 The Polarization Resistors must not be too small because a transmitter has to act against them A typical transmitter provides up to 60 mA of current in high and low level With
7. the SER 485 PRO SI the polarization option may have additional advantage As said above RS485 requires a connection of GND signals otherwise the signals at the receiver may be out of the bounds of the Common Voltage Range Since on SER 485 PRO SI the driver and polarization voltage are isolated the received signals are now in the required range As a result only two wires are required for data transmission Attention this is the situation if the SER 485 PRO SI is the only device with polarization active 7 4 2 Wire Scheme In many configurations a very simple cabling is required RS485 allows for so called 2 wire cabling as shown below Several devices are connected in parallel to the wires which is called bus topology Each device can either send or receive data at a given time so it is operating in half duplex mode Assuming group speed of 100 000km s 10 travels to damp out and 10 of bit time April 2008 SER 485 PRO SI User Manual 19 7 Proper Cabling Shown in figure 6 are three devices RS485 specifies up to 32 The data lines are named as Data and Data a positive differential voltage is the state for a transmitted One The GND is also connected between all devices as required Dev 1 Dev 2 Dev N 2 wire half duplex bus topology Figure 6 2 wire cabling scheme The resistors P1 and P2 are for polarization T1 and T2 are
8. topology Figure 7 4 wire cabling scheme Figure 7 displays the wire pairs Tx and Rx as named for Devices 1 and 2 There are more slave devices two are shown The slaves transmit on the Rx lines and receive on the Tx lines The GND line is also connected to implement the Common Voltage Range as specified Masters on the network are identified because they transmit on the Tx lines The two Masters in figure 7 have to synchronize their use of the Tx lines be extra means E g Dev 2 can be a backup master which is manually activated Also indicated in figure 7 are polarization resistors P1 P2 for Tx and P3 P4 for Rx only once per wire pair Further Termination resistors T1 T2 for Tx and T3 T4 for Rx are added one at each end of the cable To ensure the Common Voltage Range the GND is also connected at each device 8 ART and Polarization In the SER 485 PRO the automatic ART monitors the phases of high and low on the RS232 line These phases define the One and the Zero bits as well as characters The length of these phases is measured and calculated to the current bit rate Each data transmission begins with the Start bit of the first character which is a Zero bit ART activates the RS485 transmitter when this Zero is detected and sends this Zero on the RS485 wires as a negative polarity The following data and optiona
9. ER 485 PRO sends data to the RS232 port of the PC e LED3 is Red it lights when power is supplied to the SER 485 PRO 6 Configuration by Software The SER 485 PRO will usually be connected to a PC at Coml or another serial port Most computers will have a Terminal Emulation program already installed On Windows Systems this will be Hyper Terminal on Linux it is miniterm on DOS systems there are several programs like Telix or Telemate If no suitable program is installed on the target system the configuration can be done on any other computer The parameters are saved to a non volatile memory and they are activated by the DIP configuration OFF amp ON Open the Terminal Emulation in VT100 modet and configure the serial port Com1 to 115200 bps 8 Data bits No Parity and 1 Stop bit Flow Control Handshake is not used so neither RTS CTS nor XON XOFF must be active Set both DIP Switches to the OFF position and wait a few seconds The interactive menu will appear it may look like figure 2 1 ANSI Terminal Emulation is also suitable April 2008 SER 485 PRO SI User Manual 11 6 Configuration by Software www visionsystems de Operation Modes 1 RS 422 2 RS 485 controlled by RTS 3 RS 485 controlled by DTR 4 RS 485 controlled by ART a Tx switch off Delay long 11 bit b Tx switch off Delay medium 6 bit 6 Tx switch off Delay short 2 bit Cabling Schemes d Full Duplex 4 wire e Half Duplex
10. OS offered easy control of RTS to the application program However modern OS like Linux or Windows block direct access to hardware by application programs April 2008 SER 485 PRO SI User Manual 14 6 Configuration by Software Further serial speeds have been increased in the past years so fast control is a demand At 115200 bps a character lasts less than 0 1 millisecond often application software does not have simple access to such precise time control As a result some hardware automatic for control of the RS485 transmitter is required The SER 485 PRO offers such named as ART Automatic Receive Transmit control ART analyzes the transmitted signals in real time to detect the configured serial speed It adapts to that speed and sets the transmitter in On or Off state as required All data sequences begin with a Zero bit called the Start Bit This is a signal to ART to activate the transmitter When no more data is sent ART deactivates the transmitter The configuration and selection of proper parameters is explained in 6 4 1 and 8 1 This option is used if the RS485 operation is requested by the ON ON configuration of the DIP Switches 6 4 1 a Tx switch off Delay long 11 bit This is a configuration option for the ART function There is no precise and fast way to detect the end of a data transmission by analyzing the stream of bits on the line Data is transmitted as a sequence of Zero and One bits when no data is trans
11. Systems reserves the right to make improvements and or changes to this manual or to the products and or the programs described in this manual at any time Information provided in this manual is intended to be accurate and reliable However Vision Systems assumes no responsibility for its use or for any infringements on the rights of third parties that may result from its use This product might include unintentional technical or typographical errors Changes are period ically made to the information herein to correct such errors and these changes are incorporated into new editions of the publication April 2008 SER 485 PRO SI User Manual 2 Contents Contents 1 Overview 5 2 Introduction 5 3 Operation Modes 6 4 Technical Data 7 5 Configuration of Hardware 8 Bel Connectors usa a a a Be ee A ee A a A 8 52 Signal Assignments R8232 sa or a a a A 9 5 3 Signal Assignment R8422 RS485 RR ee A 9 gol CN2 DB9 421 f R545 kee ERE HR 9 53 2 181 Terminal Block R5422 RS485 eee ee cantra nas 10 5 3 3 Termination and Polarization BIAS 10 ba PORGESUBDO 2 6 0 2 4 Mena a a o A eee ee dd 10 Ba LED 2 bei eee ee dadas a is ia a ERS 11 6 Configuration by Software 11 5I IR 14 62 2 lt RS A controlled by RIS xe saec bic lr RR Ey hes 14 6 2 He 485 controlled by DIR 2 664 cacy rr a RR 14 84 4 K5 485 controlled by ART
12. a o e ee ee Aa Ph ee 22 9 Firmware Update 23 List of Figures 1 Internal view of SER 485 PRO SI o 8 2 Menu Factory Settings 2 62466 24 eee ee ee ee ee 12 3 Menu Configuration as RS422 13 4 Menu Configuration closed lt 13 5 Menu Programming Interface e 17 6 rl ll oce e ek e 20 T Aare caping ACUSE coca e kok pow Aik RRA A eed ee Ree i A 21 List of Tables 1 Operation configured by DIP Switches ee 6 2 Ro DBO temale 0 as a a aa a a Boe A a a ae a a ew a 9 3 Redes DBO mal crocea p ste ara HEE a au dae eee OS 9 4 Terminal Blok gt r iugera Re PRE Rem BO aai 10 April 2008 SER 485 PRO SI User Manual 4 2 Introduction 1 Overview The SER 485 PRO converts signals between RS232 and RS422 or RS485 It is used to convert RS232 signals to RS422 485 networks based on differential balanced electrical signals to allow reliable and long distance up to 1 3km connections In RS485 halfduplex Mode the switching on and off for Transmit and Receive lines is necessary which is usually done via software SER 485 PRO provides a unique hardware based Automatic Receive Transmit control ART mode which allows the shortest switch off time delay over the full range of the bitrate speeds ART allows the use of software applications
13. also named as BIAS Some hints for Termination are given on page 19 as well These functions are activated by relay via software configuration no need to set DIP Switches or Jumpers Termination may be applied to each end of the cable so only two termination resistors are allowed If more than two devices are connected to the cable the middle devices must deactivate their termination The value of the resistors must match the impedance of the cable used to connect the devices Polarization is allowed at a network only once It is a failure to activate this in two or more devices The polarization in the SER 485 PRO is designed for termination resistors of at least 1200 It may safely be used for higher values including no termination at all Lower impedance cables smaller resistors require special circuitry 5 4 Power supply The power input to the SER 485 PRO is very flexible The SER 485 PRO is powered by an external adapter which is connected to J2 This adapter is shipped with the SER 485 PRO The SER 485 PRO accepts any power supply as long as this follows the specifications of 9V to 30V DC The SER 485 PRO requires 80 mA at 12V the SER 485 PRO SI requests about 200 mA at 12V April 2008 SER 485 PRO SI User Manual 10 6 Configuration by Software 5 5 LED There are three LED in the SER 485 PRO e LED is Green it flickers when SER 485 PRO receives data from the RS232 port of the PC e LED2 is Yellow it flickers when S
14. and CTS are only available on this connector These signals are rarely used only in certain configurations The data signals Tx and Rx E are more common They are also available on TB1 see below April 2008 SER 485 PRO SI User Manual 5 Configuration of Hardware Using the so called 2 wire or half duplex mode the signals Tx and Tx are used to both transmit and receive the data So the signals are renamed to Data and Data Half duplex mode is only available in RS485 configurations 5 3 2 TB1 Terminal Block RS422 RS485 The Terminal Block TB1 provides the common subset of RS422 and RS485 signals i e the data signals The signal GND is also available to connect all devices together 5 1 As mentioned above in half duplex mode the signals Tx and Tx change their names to Data and Data respectively because the data is transmitted on these lines Table 4 Terminal Block 5 3 3 Termination and Polarization BIAS Termination and Polarization are important functions of RS485 data transmission Termination is used to protect against signal ringing it damps out reflected signals Polarization is required to protect against noise on the data lines at times when no device is actually transmitting data In RS422 mode the transmitter is driven permanently so polarization is only required for RS485 operation Why Polarization is important is described on page 19 polarization is
15. configurations are very common so they are available by simply setting the switches To get the full benefit of the SER 485 PRO versatility users have to use the Configura tion by Software page 6 This is not as complicated as it may sound The configuration is done in an interactive way so there is very little risk of damage When the intended configuration is saved to non volatile memory in the SER 485 PRO the DIP Switches shall be set to the OFF ON setting The third DIP switch is used to select the signal assignment of the RS232 port In the ON position the RS232 serial port is configured as DCE factory setting like a modem When connecting to April 2008 SER 485 PRO SI User Manual 6 4 Technical Data a PC Coml a straight cable is required In the OFF position the DTE configuration is selected When connecting to a PC Com1 a null modem cable is required 4 Technical Data Operation 16 different conversion modes RS232 signals TxD RxD RTS CTS DTR GND DB9 female configured as DCE or DTE RS422 signals DB9 male Tx Rx RTS CTS GND Terminal Block Tx Rx GND RS485 signals 4 wire Tx Rx RTS CTS GND 2 wire Data GND On DB9 male and Terminal Block Power 9V to 30V DC 80mA 12V for SER 485 PRO 9V to 30V DC 200 mA Q12V for SER 485 PRO SI Dimensions 67 x 90 x 27 Speed RS422 1Mbps RS485 by ART 250 kbps RS485 by RTS DTR 1 Mbps T
16. connect devices to each other April 2008 SER 485 PRO SI User Manual 15 6 Configuration by Software 6 5 1 d Full Duplex 4 wire Usually RS485 is used in the so called 2 wire mode This means data is sent and received on the same pair of wires named Data Obviously each device can either receive or send data at a given time so this mode is also called half duplex Because all devices are connected in parallel to this wire pair another name of this configuration is bus mode However there are some configurations requiring a dedicated pair to transmit data and to optionally receive data at the same time on a second pair This is similar to RS422 so in most of these cases the configuration as RS422 is more simple RS485 in 4 wire is required when there are two or more devices transmitting on a given pair while they receive on a second pair To provide this function the SER 485 PRO offers option d in the menu This is available for all control modes of the transmitter regardless of RTS DTR or ART 6 5 2 e Half Duplex 2 wire with Echo As described in option d in most situations RS485 is used with only one pair of wires for data transmission Basically this operation mode has been the reason to design specifications of RS485 Of course the SER 485 PRO offers this option also Since the same pair of wires is used to transmit and receive data the hardware can simultaneously receive the data it is just sen
17. ding This is called the Echo Software can compare the received data to that just sent this may provide an option of check for line congestion However the electrical specifications of RS485 do not guarantee to detect such a situation So the Echo is rarely used 6 5 3 f Half Duplex 2 wire no Echo The Echo as defined in option e is usually not intended Either the software has to suppress it or this task is given to the hardware Since the SER 485 PRO controls the transmitter state it can suppress any received data while it is transmitting This option is used if the RS485 operation is requested by the ON ON configuration of the DIP Switches 6 6 Cable Options 6 6 1 h Terminate Tx lines Option h controls a relay which will activate the termination resistor 1200 in the SER 485 PRO This resistor is provided for standard cables manufactured as twisted pair If a 2 wire mode is active the Tx lines are also used to receive data In such configuration this option is renamed to Terminate Data lines April 2008 SER 485 PRO SI User Manual 16 6 Configuration by Software 6 6 2 j Terminate Rx lines Option j is similar to h except the resistor is connected to the receive lines This option disappears in a 2 wire mode because the Rx lines are not used then 6 6 3 k Polarize Tx lines Option k controls a circuit to place some voltage to the Tx lines This is done via resisto
18. direction turn ART may use a delay of only 6 bit Very few characters have more than 6 consecutive One bits so this configuration is also save in standard circumstances Even when ART deactivates the RS485 transmitter because of such data the polarization as mentioned on page 19 holds the polarity on a positive level This is still recognized by the receiver as a One so the data is received correct The next Zero bit activates the RS485 transmitter again the transmission continues safe 8 3 ART 2 bit delay This short delay option is for very fast direction turn times Since many characters have 3 or more consecutive One bits there is a high likelihood for ART to deactivate the transmitter while data is transmitted As the benefit the SER 485 PRO can receive data as soon as the transmission has ended To protect against corrupted data the Polarization see on page 19 is very important When ART deactivates the RS485 transmitter the polarization ensures the data is still read as One as it is sent from RS232 It is strongly recommended to use this configuration option only when required with polarization and after careful examination of the noise level April 2008 SER 485 PRO SI User Manual 22 9 Firmware Update 9 Firmware Update Connect the SER 485 PRO to a serial port of your PC Open a Terminal Program for this serial port Configure the port to 115200 8N1 as the serial parameters and use VT100 ANSI as Emula tion when a
19. e Rx lines W Write to memory R Read from memory Enter new choice Configuration closed Figure 4 Menu Configuration closed April 2008 SER 485 PRO SI User Manual 13 6 Configuration by Software 6 1 1 RS 422 Historically RS422 has been defined before RS485 as a successor of RS232 It is much simpler to use than RS485 The transmitter is permanently active the cabling is defined as 4 wire full duplex There is no further option to configure This option is used if the RS422 operation is selected by the ON OFF configuration of the DIP Switches 6 2 2 RS 485 controlled by RTS RS485 requires to switch the transmitter Tx off when no data is sent This frees the wires they are available for another station to transmit data When data has to be sent the transmitter is activated again If the wiring uses the half duplex scheme data can be received when Tx is in the Off state In these situations the status of transmitter is also referred to as Data Direction There are different methods to control the transmitter A very common one is to use the RTS signal from the PC connected to the SER 485 PRO Most devices other converters RS485 serial ports of add on cards on the market support this method even the Windows APT for serial ports has an option to do this in an automated way Nearly all applications for control of RS485 devices provide the RTS method of transmitter control When the
20. en the task is done Please check for error messages When the update process was successful re open the serial port in the Terminal Program as before Reset the SER 485 PRO and check if the configuration menu appears again 5 Also called DOS Box April 2008 SER 485 PRO SI User Manual 23
21. ermination 1200 provided internally Polarization Provided internally for 1200 termination LED Power TxD RxD In RS422 mode the SER 485 PRO is capable of any transmission speed up to 1 Mbps This mode is used in a 4 wire full duplex configuration The RS485 mode is available in 4 wire full duplex configuration and in 2 wire half duplex configuration The later operates with or without local echo of transmitted data The transceiver data direction in half duplex mode can be controlled by RTS DTR or the automatic named as ART This automatic analyzes the transmitted data in real time and adapts to the detected bit rate The serial speeds controlled by ART range from 300 bps to 250 kbps When controlled by RTS or DTR the maximum serial speed is 1 Mbps April 2008 SER 485 PRO SI User Manual 7 5 Configuration of Hardware 5 Configuration of Hardware The operation modes of the SER 485 PRO are configured by DIP Switches and software There is no need to open the case and change jumper positions Functions of Termination and Polarization BIAS are implemented by relays and special circuits 5 1 Connectors TB1 RS422 485 Terminal Block CN1 RS232 DB9 female Figure 1 Internal view of SER 485 PRO SI CN1 is a DB9 female connector to attach the SER 485 PRO to an RS232 serial port The pin assignment is DCE like a modem as factory setting a straight connection cable to Com1 of a PC is required Using DIP3 the assi
22. for the termination function Polar ization of Data and Data appears only once on this net the termination is at the physical ends of the cable All devices appear the same on the cable they have the same function There is no Master or Slave defined by the hardware Such functions are implemented by way of the data transmission protocol Also RS485 addresses are defined by that protocol as well as bus access 7 5 4 Wire Scheme RS422 requires dedicated wire pairs for transmit and receive The transmit wires are used to send data to as many as 10 receivers as stated in the specifications of RS422 Since the SER 485 PRO uses RS485 line driver technology up to 32 receivers are possible While one pair is used to transmit a second pair is available to receive data at the same time When only two devices are connected this is a possible replacement of classic RS232 connections In RS485 4 wire mode the transmit wires may be shared between dedicated stations As an example a second station can be a backup master for the network Masters can send data and commands to one station while they receive information from another device 3See 7 3 for SER 485 PRO SI April 2008 SER 485 PRO SI User Manual 20 8 ART and Polarization Dev 1 Dev 2 Dev 3 DevN Master Master Slave Slave GND Rx Rx Tx Tx GND Rx Rx Tx Tx GND Rx Rx Tx Tx GND Rx Rx Tx Tx 4 wire full duplex
23. gnment changes to DTE like Com1 PC please check the cable carefully when attaching to the RS232 port of your device TB2 is the power input for 9 30V DC power CN2 is a DB9 male connector All signals of RS422 and RS485 are available on this connector TB1 is a Terminal Block with 5 positions The RS422 and RS485 signals Tx and Rx are in parallel to those of CN2 Of course GND is available here April 2008 SER 485 PRO SI User Manual 8 5 Configuration of Hardware 5 2 Signal Assignments RS232 The signals of RS232 are connected to CN1 the exact configuration is defined by DIP3 Pin DCE signal DTE signal 1 nc nc 2 RxD TxD 3 TxD RxD 4 DTR DSR 5 GND GND 6 DSR DTR 7 RTS CTS 8 CTS RTS 9 Opt VCC in Opt VCC in Table 2 RS232 DB9 female 543 2 1 000 0 9876 The signals RxD DSR and CTS are output and have to be connected to the input signals of Coml named the same DSR is permanently active 5 3 Signal Assignment RS422 RS485 The signals of RS422 RS485 are available on CN2 and a subset of them are connected to the Terminal Block TB1 5 3 1 CN2 DB9 RS422 RS485 Y 5 RS422 RS485 2 wire Data Data GND olol lola ona Q 4 Table 3 RS422 RS485 DB9 male 12345 6789 CN2 with the 9 pins carries the maximum of available signals The RTS
24. he SER 485 PRO to achieve normal operation Software must not send these commands When the user accidentally hits the P he can return to the menu by the lt Enter gt key The menu appears and displays the current configuration 6 8 U Firmware Update For manufacturing purposes there is an option to update the firmware of the SER 485 PRO The command U upper case starts this function If it is activated by accident the SER 485 PRO has to be restarted The process of update and the tools required for that is described in section 9 on page 23 7 Proper Cabling This paragraph will provide a little bit of theory about RS422 and RS485 data transmission It is necessary to have this basic knowledge to avoid or find errors in data transmission If you are familiar with RS485 and RS422 do not skip this section it covers common misunderstandings Failures in cabling are responsible for the vast majority of transmission problems 7 1 Transmission Technique RS422 and RS485 use the same balanced transmission method Signals are not transmitted as voltage on a single wire as RS232 does Instead two wires are used when one carries high voltage the other one carries low voltage The signal is defined by the difference in voltage between those two wires This hardens the transmission against noise Usually twisted pair cables are used which further reduces the sensitivity for noise Typical voltages are 4V as high about 0
25. l parity bits are Ones or Zeroes each character is ended with a Stop bit with value One To make a successful transmission all these bits must appear on the RS485 wires without corruption See 7 3 for SER 485 PRO SI April 2008 SER 485 PRO SI User Manual 21 8 ART and Polarization When the transmission has ended the RS232 line is in the One state Thus the RS485 line is also in the One state the positive polarity ART detects this permanent condition and deactivates the RS485 transmitter The following is discussed for 2 wire mode so ART controls the data direction Further it is recommended to have good polarization of the data lines the reason is explained on this page 8 1 ART 11 bit delay The longest possible character on RS232 has 8 data bits one Parity and two Stop Bits If all these bits are a logic One there are 11 consecutive One bits on the serial line So no matter what data is transmitted in which serial configuration ART will never switch off the transmitter while data is still transmitted However in usual 8N1 configuration the last data bit is often a Zero So ART turns the direction 10 bits after the last character which is exactly one character time This is suitable fast especially with high bit rates For specially crafted short data transmissions ART may calculate the bit rate as to low So the time of direction change may be longer than one character 8 2 ART 6 bit delay To give a faster
26. mitted the data line is also in the One state ART analyzes the data line in real time to detect the bit rate Based on this rate ART counts consecutive bits sent as One Users configure the time by giving the number of One bits to hold the transmitter active This option a guarantees the transmitter is not deactivated in the middle of a data transmission As the result the turn over time to receive state in 2 wire mode may be longer than necessary This is explained in detail on page 22 together with electrical specifications of RS485 This option is used if the RS485 operation is requested by the ON ON configuration of the DIP Switches 6 4 2 b Tx switch off Delay medium 6 bit This option provides faster turn around times to an inactive transmitter However it is long enough to have an extremely low risk of an inactive transmitter in the middle of transmitted data In many circumstances this will not happen When cabling and the electrical configuration is correct even this will not cause damaged data This is explained in detail on page 22 6 4 3 Tx switch off Delay short 2 bit This option provides very fast turn around times to an inactive transmitter However it may cause a deactivated transmitter while the data transmission is still active This requires careful configuration of cabling and electrical configuration Please read on page 22 6 5 Cabling Schemes Cabling schemes are the different possibilities to
27. receiving RS422 485 electrical stan dard allows cable lengths up to 1 2km and bitrate speeds up to 1 Mbit s The used cables are still simple twisted pair wires but the connection lines becomes long transmission lines and request therefore termination and biasing resistors RS485 mode allows multipoint connections such as Master to N Slaves but requests additional protocol for the right to use the transmit line from only one party at a time This Protocol has been implemented in software and the enable disable of each RS485 transmitter works usually over the RTS control signal This requirement for RS485 April 2008 SER 485 PRO SI User Manual 5 3 Operation Modes multipoint protocol causes RS232 applications to fail when directly used for RS485 configurations SER 485 PRO provides a unique bitrate speed adaptive ART feature which take over multipoint protocol requirements for RS485 3 Operation Modes The SER 485 PRO provides versatile operation modes These are configured by software and DIP Switches DIP1 DIP2 DIP3 Selected Operation RS485 2 wire controlled by ART HIN AN long Tx Off Delay see below OFF ON RS422 4 wire EOT Uses parameters as configured by ON OEP software page 6 Ane ae Enable configuration menu 115200 8N1 ON RS232 as DCE OFF RS232 as DTE 5 Table 1 Operation configured by DIP Switches The first two of these
28. rs matching the conditions with a 1200 termination resistor On the SER 485 PRO SI this voltage is of course isolated also If a 2 wire mode is active the Tx lines are also used to receive data In such configuration this option is renamed to Polarize Data lines 6 6 4 Polarize Rx lines Option f is similar to k except the polarization voltage is connected to the receive lines This option disappears in a 2 wire mode because the Rx lines are not used then 6 7 P Programming Interface One additional option is not shown in the menu this is for configuration by specialized programs Users may program their own applications for configuration of the SER 485 PRO Instead of reading the menu and simulating user input such configuration software may use a simpler way The software may send the character P in upper case to open another way of configuration In this interface the SER 485 PRO sends an exclamation mark as a prompt The software may send a command once this prompt is received The available commands are the same as described above i e the software sends single characters to change the configuration Wait for the prompt between the command characters These single characters are already defined they are the same keys the user may type figure 2 After each command is executed the SER 485 PRO sends the current configuration as a string listed in quotation marks This configuration is followed by
29. serial port sets RTS in the active state the SER 485 PRO activates the transmitter for Tx Later the port sets RTS as inactive and the SER 485 PRO switches the transmitter for Tx as Off The software sending the data is responsible to activate RTS before sending the data And also it is responsible to deactivate RTS when all data is sent The delay between the last data byte and RTS Off shall be as short as possible RTS and CTS are also converted to RS422 and available on CN2 the male DB9 connector Even when Tx is controlled by RTS the signal changes are reflected on CN2 RTS should not connect to other devices when it is used to change the Data Direction 6 3 3 RS 485 controlled by DTR In some configurations the signal RTS is already used on the RS485 lines for some purpose So it can not be used to control the Tx transmitter The SER 485 PRO allows to control Tx by DTR instead of RTS DTR is not converted to the RS422 RS485 lines so it is free for other purposes Software can use DTR in the same way as the RTS signal to control Tx In fact the hardware of some serial ports Ox16C950 provides options to control DTR by an internal hardware automatic Unfortunately such hardware is not available for Com1 in standard PCs 6 4 4 RS 485 controlled by ART Controlling the transmitter by a dedicated signal is a simple implementation in converter hardware so many devices used this method in the past years Using Operating Systems like D
30. vailable Otherwise use the Emulation of a Dumb Terminal Open the serial port with this configuration On the SER 485 PRO set both DIP switches to the OFF position The configuration menu will appear in the terminal program There is a possible command not displayed on the screen Enter a in upper case This is the command for firmware update The SER 485 PRO will prompt with an exclamation mark in the next line The SER 485 PRO is ready to accept the start sequence from the update software If an update is not desired it is required to reset the SER 485 PRO now In the Terminal Program close the connection to the serial port There may be a command for disconnect or simply close the program completely The serial port will be available for other software Open a console Window in the folder where the update utility vs_fw_update exe resides To simplify the update the new firmware image should also be available in that folder Issue the command vs_fw_update exe Com1 firmware bin 115200 Coml has to be replaced with the serial port the SER 485 PRO is connected to Likewise firmware bin is a place holder for the new image file The 115200 instructs the update program not to use automatic configuration The update program establishes contact to the SER 485 PRO and verifies it is really a suitable device The firmware image is sent to the SER 485 PRO and saved to the Flash memory The software returns to the command prompt wh
31. written for standard RS232 communication to be unchanged used with SER 485 PRO converter SER 485 PRO supports all possible operation modes which can be configured in detail via terminal software For reliable RS422 485 networks the termination and biasing of the lines are very important SER 485 PRO enables user to configure the lines in the optimal way SER 485 PRO comes in a IP30 metal case with wall and DIN Rail mounting capabilities The SER 485 PRO is a 100 jumper free device e Operation Modes RS422 RS485 2 wire RS485 4 wire e RS485 controlled by RTS or DTR e RS485 adaptive control by ART e Easy Software Configuration e Termination and Polarization controlled by software e Metal Case IP 30 e Galvanic isolated signals on SER 485 PRO SI This manual covers two devices the SER 485 PRO and the SER 485 PRO SI which has internal isolation and surge protection of RS422 485 signals The use of both models is the same except where explicitly noted otherwise 2 Introduction Many devices like machines printers sensors etc provide a serial interface to exchange data with them Usually this interface follows RS232 specification because of the simple technology and cable requirements There are three limitations in using RS232 connections limited length of cable at ca 13m 40 ft maximum transmission speed e g 115 kbit s on 13m cable and PointtoPoint connection only Using dual differential signals for both data transmission and
32. www vscom de lt lt lt lt lt lt ss lt lt lt lt lt eee ss eee o so lt ne o o oo o lt lo RS422 485 Converter 4 PRO SI User Manual Power Converter F H Support serviceOvisionsystems de A Tel 49 40 528 401 0 N Fax 49 40 528 401 99 Web www visionsystems de The software described in this manual is furnished under a license agreement and may be used only in accordance with the terms of that agreement Copyright Notice Copyright 2007 Vision Systems All rights reserved Reproduction without permission is pro hibited Trademarks VScom is a trademark of Vision Systems GmbH All other trademarks and brands are property of their rightful owners Disclaimer Vision Systems reserves the right to make changes and improvements to its product without pro viding notice Vision Systems provides this document as is without warranty of any kind either expressed or implied including but not limited to its particular purpose Vision
Download Pdf Manuals
Related Search