Nokeval RCS770 User manual

1
RCS770
USB / RS-485 / RS-232 converter
User Manual
23.5.2006
V1.0

INTRODUCTION
RCS770 s a general-purpose ser al converter equ pped w th a USB port, RS-232 port and two RS-485 ports.
Convers on can be done n all d rect ons. Alternat vely, th s converter can act as a RS-485 repeater allow ng
more RS-485 dev ces to be used, s nce one bus can normally hold 32 dev ces. The two RS-485 ports can be
conf gured to act as a s ngle full-duplex RS-422 port or a four-w re RS-485 port.
USB, RS-232 and RS-485 sect ons are galvan cally solated from each other, wh ch w ll el m nate ground
loops and g ve more tolerance aga nst d sturbances and overvoltages. However, the two RS-485 buses are
not solated from each other.
If RCS770 s connected to a computer v a USB, t creates a v rtual ser al port that can be used just l ke an
ord nary port. Every converter has an nd v dual ser al number, and the converter w ll reta n the same COM
port number even f plugged nto a d fferent USB port on the same computer. Th s ncreases rel ab l ty.
RCS770 s able to pass var ous ser al protocols, nclud ng Nokeval SCL, Modbus ASCII, Modbus RTU, and
HART. The RS-485 d rect on s changed automat cally, no handshake l nes are requ red.
RS-485 bus s attached v a screw term nals, avo d ng the need to make solder jo nts on f eld.
SPECIFICATIONS
USB port
Vers on: USB 1.1 or 2.0
Interface ch p: FTDI FT232R
Power consumpt on: < 200 mA
Connector: USB-B (A-B cable ncluded)
RS-485 ports
Baud rates 300…230400 b t/s, except
as a repeater 1200…
115200.
Data b ts 5…8
Par ty All supported
Stop b ts 1, 1.5 or 2 on USB, 1 on
RS-232
Bus length 1000 m max
Dev ces on bus max 32 standard dev ces or
128 1/4 load dev ces
Load 1/4 load (128 dev ces of
th s k nd can ex st on the
same bus)
Transm tter enable Automat c
RS-232 port
Connector: D9 male (DTE) (null modem
cable for PC ncluded)
Baud rates: 1200, 2400, 4800, 9600,
19200, 38400, 57600,
115200
Handshake l nes: Not controllable, l nked
nternally
External po er supply
Note: external power supply s not necessary when
the USB s used.
Voltage: 8…28 VDC
Current: <200 mA
General
D mens ons: 70x85x60 mm + connectors
Oper. temperature: -30...60 °C
Galvan c solat on: Yes, 2kV AC/DC
EMC
EMC mmun ty EN 61326
EMC em ss ons EN 61326 class B
2

CONVERSION MODE
The convers on mode and other sett ngs are done w th jumpers. To access them, the enclosure has to be
opened. Insert a small flat blade screwdr ver between the l d and the bottom part of the enclosure left or r ght
s de and pull the l d off.
The converter s factory pre-set as a USB–485 converter, all baud rates allowed. RS-485 buses are
term nated and have fa l-safes on.
Every convers on mode has a page of ts own. After these, there are some pages about nstall ng the USB
dr vers and other add t onal nformat on.
Connectors
Conn Purpose
J3 RS-485 bus 2, or RS-422 bus Tx
J4 RS-485 bus 1, or RS-422 bus Rx
J8 An external power supply can be connected here,
see page 10
J7 An external power supply can be connected here
J6 RS-232 port
J2 USB port
Indicators
LED Purpose
D1 Th s converter s powered up. USB dr vers are
work ng.
D2 Th s converter s rece v ng data from PC v a USB
D3 Th s converter s send ng data to PC v a USB
Jumpers
Jumper Purpose
J1 RS-485 bus 2 term nat on and fa l-safe
J5 RS-485 bus 1 term nat on and fa l-safe
J14 Connects the power supply of the bus dev ces and th s converter together, see page 10.
J11
Baud rate and b t format select on. Not used when USB s used.
J13 Programm ng connector for the m crocontroller. The m ddle p ns must be jumped.
J10 and J12 Convers on mode. Modes are expla ned on the follow ng pages.
J9 Closed when 485–485 repeater, open otherw se.
3
4 3 2 1 4 3 2 1 3 2 1 J7
J6
J2
J3 J4 J8
J1 J5
J10
J12
J13
J11
J9
J14
D1
D2 D3
1200 2400 4800 9600 19200 38400 57600 115200 8N1, 7E1, 7O1, 7N2 8E1, 8O1, 8N2, 9N1

USB – RS-485
Jumpers
•To set n USB – RS-485 mode, set J10 and J12 accord ng to the p cture.
•J1 and J5 def ne the 485 bus term nat on, see page 12.
•J14 controls the power supply opt ons, see page 10.
•J11 and J9 are not used.
Connections
•USB s connected to a computer. See page 11 on dr vers.
•RS-485 buses J3 are J4 equal. Any or both of them may be used. See page 12.
•No external power supply s requ red, but J8 can be used to power up the RS-485 dev ces connected n
connectors J3 and J4. The power supply s routed from J8 to J3 term nal 1 and J4 term nal 1.
4
Power
supply
(opt onal)
4 3 2 1 4 3 2 1 3 2 1 J7
J6
J2
J3 J4 J8
J1 J5
J10
J12
J13
J11
J9
J14
D1
D2 D3
USB
RS-485
dev ce
C
D1D0 + C +

USB – RS-422
Jumpers
•Set J10 and J12 accord ng to the p cture.
•J1 and J5 def ne the 485 bus term nat on, see page 12.
•J14 controls the power supply opt ons, see page 10.
•J11 and J9 are not used.
Connections
•USB s connected to a computer. See page 11 on dr vers.
•J3 and J4 are the RS-422 bus. Th s dev ce transm ts at J3 and rece ves at J4.
•No external power supply s requ red.
5
Power
supply
(opt onal)
4 3 2 1 4 3 2 1 3 2 1 J7
J6
J2
J3 J4 J8
J1 J5
J10
J12
J13
J11
J9
J14
D1
D2 D3
USB
RS-422
dev ce
C
T1T0 + C + R1R0
Rx- Rx+ Tx- Tx+ Common Power

USB – RS-232
Jumpers
•The USB–232 mode s selected w th jumpers J9, J10, and J12 accord ng to the p cture.
•J1, J5, J11, and J14 have no effect.
Connections
•USB s connected to a computer. See page 11 on dr vers.
•How to use the RS-232 bus, see page 15.
•No external power supply s needed.
6
4 3 2 1 4 3 2 1 3 2 1 J7
J2
J3 J4 J8
J1 J5
J10
J12
J13
J11
J9
J14
D1
D2 D3
USB
J6
RS-232

RS-232 – RS-485
Jumpers
•To select 232–485 mode, set jumpers J9, J10, and J12 accord ng to the p cture.
•J1 and J5 select the 485 bus term nat ons, see page 12.
•J14 controls the power supply flow onto the bus, see page 10.
•J11 s used to control the baud rate and b t format:
Connections
•RS-485 buses J3 and J4 are equal. Any or both of them may be used. See page 12.
•RS-232 bus s expla ned on page 15.
•Th s converter must be powered externally on J7 or J8, see page 10.
7
4 3 2 1 4 3 2 1 3 2 1
J6
J2
J3 J4 J8
J1 J5
J10
J12
J13
J11
J9
J14
D1
D2 D3
RS-485
dev ce
CD1D0 +
RS-232
Mascot
J7
+-
1200 2400 4800 9600 19200 38400 57600 115200 8N1, 7E1, 7O1, 7N2 8E1, 8O1, 8N2, 9N1

RS-232 – RS-422
Jumpers
•232–422 mode s selected w th jumpers J9, J10, and
J12 accord ng to the p cture.
•J1 and J5 def ne 422 bus term nat on, see page 14.
•J14 controls power supply opt ons, see page 10.
•J11 selects the baud rate and b t format, see p cture
below.
Connectors
•J3 s RS-422 Tx and J4 s Rx. See page 14.
•RS-232 s expla ned on page 15.
•An external power supply must be connected n J7 or
J8, see page 10.
8
4 3 2 1 4 3 2 1 3 2 1
J6
J2
J3 J4 J8
J1 J5
J10
J12
J13
J11
J9
J14
D1
D2 D3
RS-232
+-
RS-422
dev ce
C
T1T0 + R1R0
Rx- Rx+ Tx- Tx+ Common Power
Mascot
J7
1200 2400 4800 9600 19200 38400 57600 115200 8N1, 7E1, 7O1, 7N2 8E1, 8O1, 8N2, 9N1

RS-485 REPEATER
Jumpers
•485 repeater mode s selected w th jumpers J9, J10, and J12 accord ng to the p cture.
•J1 and J5 def ne the 485 bus term nat on, see page 12.
•J14 controls the power supply opt ons, see page 10.
•J11 selects the baud rate and b t format:
Connectors
•J3 and J4 are the RS-485 buses. Data on e ther bus s repeated onto the other.
•Th s converter must be powered up from an external supply brought to connector J7 or J8. See page 10.
9
4 3 2 1 4 3 2 1 3 2 1
J6
J2
J3 J4 J8
J1 J5
J10
J12
J13
J11
J9
J14
D1
D2 D3
RS-485
dev ce
C
D1D0 +J7
RS-485
dev ce
C
D1D0 +
Mascot
9V
1200 2400 4800 9600 19200 38400 57600 115200 8N1, 7E1, 7O1, 7N2 8E1, 8O1, 8N2, 9N1

SUPPLY VOLTAGE
Supply voltage for RCS770
If USB s used, RCS770 does not need other power supply for tself. If USB s not used, an external power
supply s needed.
The external supply s connected to connector J7 or J8. If you use J8, read the sect on ”Jumper J14” below.
J7 s a 1.3 mm DC jack and t accepts voltage between 8 and 28 VDC. If 230 VAC socket s ava lable,
Nokeval recommends Mascot 8311-9V-3635 AC/DC adaptor, ava lable separately.
Supply voltage for the bus devices
It s somet mes conven ent to bu ld the RS-485 bus w th a four w re cable cons st ng of common, power
supply, and two data l nes. Th s s why RCS770 has four term nals on each bus connector: one of the
term nals s reserved for supply voltage. RCS770 does not generate th s supply voltage and t must be
brought to connector J8 or J7. If you use J7, read the sect on ”Jumper J14” below.
RCS770 tself does not care wh ch way the bus dev ces are powered. Th s power supply rout ng s prov ded
only to make the cabl ng eas er.
The voltage can be anyth ng as long as t does not exceed 30 VDC because there s a 33 V var stor
protect ng from voltage surges.
Jumper J14
If jumper J14 s open, J7 s used to prov de the supply voltage for RCS770 tself and J8 s used to prov de the
supply voltage for the RS-485 bus dev ces.
If jumper J14 s closed, these two c rcu ts are nterconnected. You can br ng the external power supply at
e ther J7 or J8 and n both cases the same power supply w ll be used for both RCS770 and the bus dev ces.
10
3 24 3
Supply
24V
3 241 2 11
+-
USB
Mascot
RS-232
485 c rcu ts
232 c rcu ts
J14
J3 J4 J8
J7
Separate supply for
RCS770 and bus
dev ces
Common supply
J14
Isolat on

USB
Installing the drivers
There are two ways to nstall the USB dr vers.
Found Ne Hard are izard
If you just plug n the dev ce, the Found New Hardware
w zard w ll be tr ggered.
The dr vers can be obta ned from:
•Nokeval Software CD or
•W ndows Update (XP only)
•Downloaded from the USB ch p manufacturer http://www.ftd ch p.com/, VCP dr vers for FT232R.
The w zard s launched tw ce: the f rst dr vers are the USB dr vers, and the second dr ver creates a v rtual
ser al port n W ndows.
Pre-installing the driver
Another way to nstall the dr vers s to run a setup f le n the Nokeval Software CD before plugg ng n the
dev ce. The dev ce can then be plugged n and all s done.
When the dr vers are successfully nstalled, the power nd cator on RCS770 should l ght up.
Virtual serial port
The USB dr ver creates a v rtual COM port n the next unused port number. To f nd out wh ch port we got, go
to the Dev ce Manager (Control Panel, System, Hardware, Dev ce Manager). In the dev ce tree, expand
branch Ports, and you should see e.g. USB Ser al Port (COM3).
If you double cl ck the port, you can change ts propert es. The most useful th ng s the ab l ty to change the
port number (Port Sett ngs, Advanced).
USB hubs
If RCS770 s connected to a USB hub, the hub should have a power supply of ts own as always f any of the
dev ces draw more than 100 mA current.
11

RS-485 BUSES
The RS-485 bus has two data l nes del ver ng the data. The polar ty of the voltage between the l nes def nes
whether a b t nd cat ng 'zero' or 'one' s be ng transferred. Several dev ces can be attached to the bus. Only
one of them can transm t at a t me, wh le the others l sten. Thus the commun cat on s half-duplex.
Connections
RCS770 has four term nals for each RS-485 bus: D1, D0, Common, and +. The f rst three of these form the
RS-485 bus and the fourth, opt onal l ne allows easy power supply w r ng for the bus dev ces.
D1, D0, and Common are w red one-to-one to the other dev ces on the bus. D1 and D0 are the data l nes.
Common s needed to remove potent al d fferences between the dev ces, and t may serve as the negat ve
power supply w re too.
Some older dev ces do not have a Common term nal ava lable. In that case, connect the l nes D1 and D0
only. If RCS770 s not wanted to term nate, set the jumpers J1 and J5 to ”2-w re” pos t on nstead of ”Not
term”.
The two buses (J3 and J4) are equal. The data com ng from USB or RS-232 s transm tted on both of the
buses, and data com ng from e ther of the buses s del vered to USB or RS-232.
There has been qu te r ch use of names for the data l nes. Even EIA/TIA recommended ”A” and ”B” have
been used w th two mean ngs. Nokeval has dec ded to use the names def ned by Modbus standard, D1 and
D0. The table below l sts
common names for the
l nes:
D1 D0
+ -
B A
A B
Cable
The D1 and D0 should be of a tw sted pa r, m n mum d ameter 0.5 mm (24 AWG). In a no sy env ronment a
sh elded cable should be used, the sh eld grounded at one end only.
A da sy-cha n w r ng topology s recommended. If braches or stubs are made, they should be only a couple of
meters long.
Terminating and fail-safes
If the bus s longer than some dozens of meters or f h gh baud rates are used, the bus must be term nated n
order to avo d reflect ng the s gnal from the bus ends. The reflect ons w ll cause b t errors.
Fa l-safe res stors are needed to ensure the correct state on the bus when nobody s transm tt ng. They
create va voltage of at least 0.2 V between l nes D1 and D0. Each bus should have only one dev ce fa l-
saf ng.
The term nat on and fa l-safes of RCS770 are
controlled w th jumpers J1 (for bus at J3) and
J5 (for bus at J4). Factory sett ng s both fa l-
safes and term nat on on.
The term nat on prov ded by RCS770 s of AC type: the term nat ng res stor (110 ohms) has a capac tor n
ser es (1 nF). The fa l-safes are 500 ohms from D1 l ne to +5V and 500 ohms from D0 l ne to ground.
12
Not term Terminated Term + FS 2- ire
RCS770
3 2 1
J3 J4
J1 J5
RS-485
dev ce
RS-485 bus
RS-485
dev ce
CD1D0CD1D0 4 3 2 1 4 3 2 1
RS-485 bus

Direction control
USB
When a computer sends data v a USB, the RS-485 transm tters are enabled automat cally. When the last b t
has been transm tted, the transm tters are mmed ately d sabled n order to be able to rece ve data from the
RS-485 bus.
RS-232
When some data s sent to RCS770 v a RS-232, RCS770 buffers t one byte durat on. After that, t act vates
the RS-485 transm tters, wa ts another 1/2 bytes and then starts transm tt ng the data on the bus. When the
last b t has been transm tted, the RS-485 transm tter s d sabled to allow rece v ng data.
Because the d rect on s controlled automat cally, the RS-232 handshake l nes are not used.
RS-485 repeater
RCS770 l stens to both buses. When data s rece ved from e ther bus, the transm tter of the other bus s
enabled and the data s repeated there 1.5 bytes delayed. When there s no ncom ng data for 1/2 bytes, the
transm tter s d sabled and both buses are l stened to aga n.
13

RS-422 BUS
RS-422 bus cons sts of two separate w re pa rs, one for each d rect on. Th s allows full duplex
commun cat ons.
Connections
The w re pa r carry ng data from RCS770 to the
other dev ce s connected n connector J3, and
the other pa r s connected n connector J4. In
add t on, a Common or potent al equal sat on
w re should be connected from connector J4
term nal 2 to the other dev ce.
There are var ous names for the RS-422 l nes,
but the table below l sts some:
Term nal J3.3 J3.4 J4.3 J4.4
Modbus TXD1 TXD0 RXD1 RXD0
Old Tx+ Tx- Rx+ Rx-
Cable
The cable should cons st of tw sted pa rs so that
TXD1 and TXD0 form one pa r and RXD1 and
RXD0 another. The m n mum recommended d ameter for the cable s 0.5 mm (24 AWG). In a no sy
env ronment a sh elded cable should be used, the sh eld grounded at one end only.
Terminating and fail-safes
In RS-422 bus, both w re pa rs have always one transm tter enabled. There s no benef t n term nat ng or fa l-
saf ng the transm tt ng end of the w re pa r. So t s recommended to enable the term nat on and fa l-safes of
the rece v ng end only: n RCS770, jumpers J1 should be set ”Not term” and J5 ”Term + FS”.
14
Not term Terminated Term + FS
3 2 1
RS-422 dev ce
D1D0
4 3 2 1
Power supply
+-3 2 14
RCS770
J3 Tx J4 Rx J8
CD1D0 +
Rx Tx

RS-232 PORT
Pins
The RS-232 port of RCS770 s of ”DTE” or ”data term nal equ pment” type, s m lar to the port on PC's. So
RS-232 dev ces can be connected to RCS770 w th s m lar cable that would be used between the dev ce and
a PC.
If RCS770 s connected to a PC us ng an RS-232 bus, a cross-connected (also called as ”null-modem”)
cable must be used. It s enough to connect p ns 2-3, 3-2, and 5-5.
Pin Name Purpose Direction
1 DCD Carr er detected In
2 RxD Data rece ve In
3 TxD Data transm t Out
4 DTR RCS770 s ready Out
5 Gnd Ground
6 DSR Other dev ce s ready In
7 RTS RCS770 requests to send Out
8 CTS Other dev ce allows to send In
9 RI Telephone r ng ng In
Handshake lines
RCS770 s ntended to be pr mar ly a USB-RS-485 or RS-232-RS-485 converter, not USB-RS-232, although
poss ble. Consequently the RS-232 handshake l nes are not controllable, but they are nterconnected as
follows:
DTR s connected to DCD and DSR. RTS s connected to CTS.
15
12345
6 7 8 9

TROUBLESHOOTING
The nd cator l ghts are useful n troubleshoot ng. Unfortunately the Tx and Rx nd cators work only when USB
s used.
Step 1: Drivers and supply voltage
Is nd cator D1 l t?
•Yes: go to step 2.
•No and USB s used: re nstall the dr vers.
•No and USB s not used: check that there s an external power supply connected n J7 or J8. If the power
supply s connected n J8, make sure that jumper J14 s closed.
Step 2: Transmission
Start the appl cat on on PC. Exam ne, f the Tx nd cator s bl nk ng. If not, the appl cat on s us ng a wrong
COM port probably. Th s test s not appl cable f USB s not used.
Step 3: Reception
If Tx s bl nk ng but Rx s not, your RS-485 dev ce s not respond ng. Check that t s powered up, the
connect ons are correct, and the baud rate and ser al address are correct.
Step 4: Bus voltage RS-485
Use a mult meter to measure the voltage between data l nes D1 and D0. It should be 0.2 to 5.0 volts, D1
be ng the pos t ve. If the voltage s 0, the bus s short-c rcu ted or there are no fa l-safes.
Measure the voltage at each bus dev ce and pay attent on that the polar ty s correct (D1 pos t ve).
16
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