MODBUS IP - Elmarksupport.elmark.com.pl/unitronics/PDF/MODBUS_IP.pdf · model number. In addition, note that the Ethernet port is an RJ-45-type port that is lined with metal. Unitronics

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MODBUS IP 9/03

Table Of Contents MODBUS IP............................................................................................................................... 1

Using MODBUS................................................................................................................... 1 MODBUS: Configuration ......................................................................................................... 3

Vision Slaves....................................................................................................................... 5 MODBUS: Scan...................................................................................................................... 7 Read Coils (1)......................................................................................................................... 8 Read Inputs (2) ......................................................................................................................10 Read Holding Registers (3) ....................................................................................................11 Read Float Registers (3) ........................................................................................................13 Read Input Registers (4) ........................................................................................................14 Read Input Float Registers (4)................................................................................................16 Force Coil (5) .........................................................................................................................17 Preset Holding Register (6) ....................................................................................................19 Loopback Test (8) ..................................................................................................................20 Force Coils (15) .....................................................................................................................21 Preset Holding Registers (16).................................................................................................22 Preset Float Registers (16).....................................................................................................23 Configuring a MODBUS slave device .....................................................................................25 Slave Addressing ...................................................................................................................26

Slave Address Tables.........................................................................................................26 MODBUS Error Table ............................................................................................................29

Index .........................................................................................................................................31

1

MODBUS IP

If your controller comprises an Ethernet card, you can use MODBUS IP commands with any connected device that supports the MODBUS protocol. Any controller in the network may function as either master or slave via the controller's Ethernet port. Ethernet uses star topology.

V2xx Vision OPLCs can be ordered with or without an Ethernet port. The Ethernet port enables you to implement communications via TCP/IP, such as MODBUS over TCP. To check if your Vision controller was supplied with an installed Ethernet port, first check the device’s model number. In addition, note that the Ethernet port is an RJ-45-type port that is lined with metal.

Unitronics currently supports both TCP and UDP, as explained in the topic About Ethernet. This topic also contains general information about Ethernet, IP addressing, sockets, and ports.

Specific information on implementing Ethernet is provided in the topic Using Ethernet.

Using MODBUS

Before using a MODBUS IP operation in your application, you must:

Assign IP addresses to both master and slave devices. This is done by placing Ethernet Card Init FBs in the ladder application of both master and slave.

Include at least 1 MODBUS Configuration FB in the ladder application of both master and slave.

The condition that activates the Configuration must turn ON for a single program scan (positive transition recommended) However, the MODBUS configuration must be scanned during every program cycle--after the Configuration is activated. One way to ensure this is by placing the configuration in the first subroutine of the main module.

Enable slave devices to be accessed by placing a Scan FB in the slave's Ladder application.

The figure below shows the elements required to carry out a Read Coils Operation.

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Note that the operand addresses in slave PLCs are indirect addresses (pointers).

MODBUS IP Operations are located on the FBs menu.

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M O D B U S : C o n f i g u r a t i o n

M O D B U S : S c a n

M O D B U S : R e a d C o i l s ( 1 )

M O D B U S : R e a d I n p u t s ( 2 )

R e a d H o l d i n g R e g i s t e r s ( 3 )

R e a d F l o a t R e g i s t e r s ( 3 )

R e a d I n p u t R e g i s t e r s ( 4 )

R e a d F l o a t I n p u t R e g i s t e r s ( 4 )

F o r c e C o i l ( 5 )

P r e s e t H o l d i n g R e g i s t e r ( 6 )

F o r c e C o i l s ( 1 5 )

P r e s e t H o l d i n g R e g i s t e r s ( 1 6 )

P r e s e t F l o a t R e g i s t e r s ( 1 6 )

E x a m p l e s

To locate application examples, select Examples from the Help menu.

MODBUS: Configuration A MODBUS Configuration FB must be included in both master and slave Ladder applications as shown below. MODBUS IP Operations are located on the FBs menu.

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Parameter Type Function

P or t Nu mb er

C ons t an t C l ic k t h e d r op- d own ar r ows t o v i ew avai l ab l e p or ts ; c l i c k t h e p or t y ou wan t t o us e.

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N et wor k ID C ons t an t T h is nu mb er i d en t i f i es th e d e vic e on t h e n et wor k. You c an e i th er ass i gn an ID v i a an MI , or d i r ec t l y v i a a c on s t an t n u mb er . T h e un i t ID r an g e is f r om 0- 2 55 . D o n ot ass ig n t h e s am e ID n u m b er t o m or e th an on e d e vic e.

T ime ou t C ons t an t or M I

T his is t h e amou n t of t i me a mas t er d e vic e w i l l wai t f or an ans wer f rom a s l a ve. T i me ou t u n i ts ar e d ef i n ed i n 10 ms ecs ; a T i me ou t v a l u e of 1 0 0 is eq u al t o 1 s ec on d.

R et r i es C ons t an t or M I

T his is t h e n umb er of t i mes a d evi c e w i l l t r y t o s en d a mess ag e.

Fu nc t i on i n Pr ogr ess

MB T his b i t is ON wh en MODBU S is ac t i ve. Us e th is as a c on d i t i on b i t f or MODB US op er at i ons t o avoi d c ommu nic at i on c onf l i c ts .

Note �

Indirectly addressed parameters in a MODBUS Configuration FB are only read when the Configuration is called. Since a Configuration is generally called as a power-up task, if, for example Retries has been indirectly addressed, and the linked MI is updated, the new value will not be read into the Configuration. The value will only be updated until the Configuration is called.

Note �

While a master attempts to send a command, the Function In Progress bit is ON. The number of attempts that the master will make is the number in Retries +1, where '1' is the initial access attempt.

Note �

When a master attempts to access a slave device, and the slave does not answer,- the Function In Progress bit will turn ON. This bit will remain on according to the following: (the number of retries + 1) x (Time Out), where '1' is the initial access attempt. Note that the Time Out parameter is in units of 10 msec.

Vision Slaves

In order to access Vision Controllers as slave devices and implement MODBUS commands, you must enter the IP addresses of the slave devices in the MODBUS IP configuration. This means that you must first assign IP addresses to each slave. This is done via the Ethernet Card Init FB, which must be configured as described in the topic Using_Ethernet.

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Note �

Slave IP addresses can also be linked to an MI vector, note that the vector is 4 MIs long. The low byte of each MI provides the number for an octet within the IP address.

If, for example, the IP address is linked to MI 0, and the low bytes of MI 0 to MI 3 contain the values 192, 198, 192, 45, the IP address will be 192.198.192. 45.

The Ladder application below enables the controller act as a MODBUS master and read coils in a slave PLC. The same PLC can also act as a slave, if a Scan operation is included in the application.

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MODBUS: Scan This enables a master device to access a slave PLC. MODBUS IP Operations are located on the FBs menu.

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Read Coils (1) Use this command to read the status of a selected group of coils and write them into a vector. The coil's status is written into a vector of MBs in the master PLC. MODBUS IP Operations are located on the FBs menu.

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Sl ave ID C ons t an t or M I

T h e IP ad dr ess of th e s l ave d e vic e c on t a i n in g t h e c o i l s t o b e r ead ( d at a s ou rc e) .

S l ave: S t ar t of V ec t or

C ons t an t , MI , ML, or DW

T h e s t ar t o f t h e vec t or o f c o i ls t o b e r ead ( d at a s ou rc e) .

R ead : V ec t or L en gt h

C ons t an t or M I

T h e v ec t or l en g th .

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Mas t er : S t ar t of V ec t or

MB T his is t h e s t ar t of a vec t or of MBs th at w i l l c on t a i n th e c o i ls ' s t at us i n t h e mas t er ( d at a d es t i n at i on ) .

Er r or S t at us MI Sh ows an er r or mess ag e n u mb er . T o d i ag n os e th e er r or , ch ec k th e MODBU S Er r or T abl e.

T ot a l S ess i ons DW T his is t h e n umb er of t i mes t h e mas t er P LC w i l l a t t em pt t o acc ess th e s l ave d e vic e. N ot e th at t h is is a s i mpl e inc r em en t a l c oun t er . I n i t i a l i ze i t b y s t or i n g 0 i n t o th e s el ec t ed DW .

Ac k n owl ed g em en ts DW T his is t h e n umb er of t i mes t h e s l ave d e vic e ans wers .

Read Inputs (2) Use this command to read the status of a selected group of inputs in a slave device and write them into a vector. The inputs's status is written into a vector of MBs in the master PLC. MODBUS IP Operations are located on the FBs menu.

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T h e IP ad dr ess of th e s l ave d e vic e c on t a i n in g t h e i n p uts t o b e r ead ( d at a s ourc e) .



T h e s t ar t o f t h e vec t or o f in p uts t o b e r ead (d at a s our c e) .


C ons t an t or M I



MB T his is t h e s t ar t of a vec t or of MBs th at w i l l c on t a i n th e in p uts ' s t a t us in t h e mas t er (d at a d es t i n at i on ) .




Read Holding Registers (3) Use this command to read the values of a selected group of registers in a slave PLC and write them into a defined vector of registers in the master. MODBUS IP Operations are located on the FBs menu.

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T h e I P ad dr ess of t h e d ev i c e c ont a i n i ng t h e r eg is t ers t o b e r ead ( d at a s ou rc e) .



T h e s t ar t o f t h e vec t or o f r eg is t ers t o b e r e ad ( d at a s o urc e) .



T h e vec t or l eng th N ot e � A MOD BUS c omman d c ann ot r e ad mor e t h an 1 24 16-b i t in t eg ers , 6 2 d ou b l e r eg is t ers , or 6 4 f l oat r eg is t ers a t on e t i me. I n ad d i t i on , 0 is n ot a l eg al l en gt h. � I f , w i t h in t h e S l a ve: S t ar t of V ec t or p ar amet er , t h e s el ec t ed r eg is t er t yp e is a 32- b i t d ou b l e r eg is t er (s l av e ad dr ess es 5 1 00 an d gr e at er ) t h e p r es et vec t or l en gt h mus t b e d ou bl ed as wel l . I f , f or e xamp l e: - S l ave: S t ar t o f V ec t or p ar am et er is s et t o 6 30 0 , an d - You w ish t o pr es et 4 r eg is t ers , f or a t o t a l of 1 6

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byt es - You mus t s et t h e P r es et V ec t or l en g th t o 8 . N ot e t h at th is mean s t h at , i n th es e c as es , t h e Pr es et : V ec t or L en g t h p ar am et er w i l l a l wa ys b e an e ven n u m b er .


MI T his is t h e s t ar t of a vec t or of MIs th at w i l l c on t a i n th e r eg is t ers ' va l u es in t h e mas t er ( d at a d es t in at i on ) .




0 is not a legal vector length

Read Float Registers (3) Use this command to read the values of a selected group of floating point registers in a slave device and write them into a defined vector of registers in the master. Values after the decimal point are rounded to the nearest whole value. MODBUS IP Operations are located on the FBs menu.

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T h e vec t or l eng th N ot e � A MOD BUS c omman d c ann ot r e ad mor e t h an 1 24 16-b i t in t eg ers , 6 2 d ou b l e r eg is t ers , or 6 4 f l oat r eg is t ers a t on e t i me. I n ad d i t i on , 0 is n ot a l eg al l en gt h. � I f , w i t h in t h e S l a ve: S t ar t of V ec t or p ar amet er , t h e s el ec t ed r eg is t er t yp e is a 32- b i t d ou b l e r eg is t er (s l av e ad dr ess es 5 1 00 an d gr e at er ) t h e p r es et vec t or l en gt h mus t b e d ou bl ed as wel l . I f , f or e xamp l e: - S l ave: S t ar t o f V ec t or p ar am et er is s et t o 6 30 0 , an d - You w ish t o pr es et 4 r eg is t ers , f or a t o t a l of 1 6 byt es - You mus t s et t h e P r es et V ec t or l en g th t o 8 . N ot e t h at th is mean s t h at , i n th es e c as es , t h e Pr es et : V ec t or L en g t h p ar am et er w i l l a l wa ys b e an e ven n u m b er .






Read Input Registers (4) Use this command to read the values of a selected group of registers in a slave PLC and write them into a defined vector of registers in the master. MODBUS IP Operations are located on the FBs menu.

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T h e vec t or l eng th N ot e � A MOD BUS c omman d c ann ot r e ad mor e t h an 1 24 16-b i t in t eg ers , 6 2 d ou b l e r eg is t ers , or 6 4 f l oat r eg is t ers a t on e t i me. I n ad d i t i on , 0 is n ot a l eg al l en gt h. � I f , w i t h in t h e S l a ve: S t ar t of V ec t or p ar amet er , t h e s el ec t ed r eg is t er t yp e is a 32- b i t d ou b l e r eg is t er (s l av e ad dr ess es 5 1 00 an d gr e at er ) t h e p r es et vec t or l en gt h mus t b e d ou bl ed as wel l . I f , f or e xamp l e: - S l ave: S t ar t o f V ec t or p ar am et er is s et t o 6 30 0 , an d - You w ish t o pr es et 4 r eg is t ers , f or a t o t a l of 1 6

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byt es - You mus t s et t h e P r es et V ec t or l en g th t o 8 . N ot e t h at th is mean s t h at , i n th es e c as es , t h e Pr es et : V ec t or L en g t h p ar am et er w i l l a l wa ys b e an e ven n u m b er .






Read Input Float Registers (4) Use this command to read the values of a selected group of floating point registers in a slave device and write them into a defined vector of registers in the master. Values after the decimal point are rounded to the nearest whole value. MODBUS IP Operations are located on the FBs menu.

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T h e s t ar t o f t h e vec t or o f r eg is t ers t o b e r e ad ( d at a s o urc e) . � I f , w i t h in t h e S l a ve: S t ar t of V ec t or p ar amet er , t h e s el ec t ed r eg is t er t yp e is a 32- b i t d ou b l e r eg is t er (s l av e ad dr ess es 5 1 00 an d gr e at er ) t h e p r es et vec t or l en gt h mus t b e d ou bl ed as wel l . I f , f or e xamp l e: - S l ave: S t ar t o f V ec t or p ar am et er is s et t o 6 30 0 , an d - You w ish t o pr es et 4 r eg is t ers , f or a t o t a l of 1 6 byt es - You mus t s et t h e P r es et V ec t or l en g th t o 8 . N ot e t h at th is mean s t h at , i n th es e c as es , t h e Pr es et : V ec t or L en g t h p ar am et er w i l l a l wa ys b e an e ven n u m b er .



T h e vec t or l eng th N ot e � A MOD BUS c omman d c ann ot r e ad mor e t h an 1 24 16-b i t in t eg ers , 6 2 d ou b l e r eg is t ers , or 6 4 f l oat r eg is t ers a t on e t i me. I n ad d i t i on , 0 is n ot a l eg al l en gt h.






Force Coil (5) Use this command to force the status of a selected coil in a slave PLC. The coil's status is forced according to the status of a selected MB in the master PLC. MODBUS IP Operations are located on the FBs menu.

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T h e I P ad dr ess of t h e d ev i c e c ont a i n i ng t h e c o i l t o b e f orc ed ( d at a s ou rc e) .

S l ave A dd r ess


T h e ad d r ess of t h e c o i l t o b e f orc ed ( d at a t ar g et ) .

V alu e t o F orc e M, S B, I , O ,T

T his MB is l oc at ed i n t h e mas t er P LC ; th is MB c ont a i n s th e s t at us t o b e f orc ed ( d at a s ourc e) . I f , f or examp l e, t h e s t at us of t h is MB is O FF , t h e s t a tus of th e c o i l i n th e s l ave w i l l b e f orc ed t o OF F.


T ot a l S ess i ons DW T his is t h e n umb er of t i mes t h e mas t er P LC w i l l a t t em pt t o acc ess th e s l ave d e vic e. N ot e th at t h is is a s i mpl e inc r em en t a l c oun t er . I n i t i a l i ze i t b y s t or i n g 0 i n t o th e

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s el ec t ed DW .


Preset Holding Register (6) Use this command to preset the value of a single register in a slave PLC. The value is set in a register contained in the master PLC. MODBUS IP Operations are located on the FBs menu.



T h e I P ad dr ess of t h e d ev i c e c ont a i n i ng t h e r eg is t er t o b e pr es et ( t arg et ) .

S l ave: O p er an d Ad dr ess


T h e ad d r ess of t h e r eg is t er t o b e p r es et ( t ar g et ) .

V alu e t o P r es et C ons t an t , T h is is t h e ad d r ess of t h e r eg is t er c on t a i n i n g t h e va l u e in

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MI , S I , ML, S L, DW , SDW or T

th e mas t er P LC (s ourc e) . T h is va l u e w i l l b e wr i t t en i n t o th e s l ave 's r eg is t er , t h e r eg is t er t h at is t o b e p r es et .

S t at us MI Sh ows an er r or mess ag e n u mb er . T o d i ag n os e th e er r or , ch ec k th e MODBU S Er r or T abl e.



Loopback Test (8) Use this command to send a test message to a slave device and receive Acknowledgements when communications are functioning properly. MODBUS IP Operations are located on the FBs menu.


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T h e I P ad dr ess of t h e d evi c e t o b e c h ec ked .




Force Coils (15) Use this command to force the status of a selected group of coils in a slave PLC. The coils' status is forced according to the status of a group of MBs in the master PLC. MODBUS IP Operations are located on the FBs menu.

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T h e IP ad dr ess of th e s l ave d e vic e c on t a i n in g t h e c o i l s t o b e f orc ed ( t arg et ) .

S l ave: St ar t of V ec t or


T h e s t ar t o f t h e vec t or o f c o i ls t o b e f orc ed (d at a t ar g et ) .


MI , SB, I , O ,T

T his is t h e s t ar t of a vec t or of MBs th at w i l l c on t a i n th e c o i ls ' s t at us i n t h e mas t er ( d at a s ourc e) .

F orc e: V ec t or L en gt h

C ons t an t or M I





Preset Holding Registers (16) Use this command to preset the value of a group of registers in a slave PLC. The values are set in a vector of registers contained in the master PLC. MODBUS IP Operations are located on the FBs menu.

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T h e IP ad dr ess of th e d e vic e c on t a i n in g th e r eg is t ers t o b e pr es et ( t arg et ) .



T h e s t ar t o f t h e vec t or o f r eg is t ers t o b e pr es et ( t arg e t ) .


C ons t an t , MI , S I , ML, S L, DW , SDW or T

T his is t h e s t ar t of a vec t or of MIs th at w i l l c on t a i n th e r eg is t ers ' va l u es in t h e mas t er ( d at a s ou rc e) .

Pr es et : V ec t or L en gt h


T h e l en gt h of th e vec t or of r eg is t ers i n b ot h mas t er an d s l ave. N ot e � A MOD BUS c omman d c ann ot r e ad mor e t h an 1 24 16-b i t in t eg ers , 6 2 d ou b l e r eg is t ers , or 6 4 f l oat r eg is t ers a t on e t i me. I n ad d i t i on , 0 is n ot a l eg al l en gt h. � I f , w i t h in t h e S l a ve: S t ar t of V ec t or p ar amet er , t h e s el ec t ed r eg is t er t yp e is a 32- b i t d ou b l e r eg is t er (s l av e ad dr ess es 5 1 00 an d gr e at er ) t h e p r es et vec t or l en gt h mus t b e d ou bl ed as wel l . I f , f or e xamp l e: - S l ave: S t ar t o f V ec t or p ar am et er is s et t o 6 30 0 , an d - You w ish t o pr es et 4 r eg is t ers , f or a t o t a l of 1 6 byt es - You mus t s et t h e P r es et V ec t or l en g th t o 8 . N ot e t h at th is mean s t h at , i n th es e c as es , t h e Pr es et : V ec t or L en g t h p ar am et er w i l l a l wa ys b e an e ven n u m b er .




Preset Float Registers (16) Use this command to preset the value of a group of floating point registers in a slave PLC. The values are set in a vector of registers contained in the master PLC. Values after the decimal point are rounded to the nearest whole value. MODBUS IP Operations are located on the FBs menu.

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T h e IP ad dr ess of th e d e vic e c on t a i n in g th e r eg is t er t o b e pr es et ( t arg et ) .



T h e ad d r ess of t h e r eg is t er t o b e p r es et ( t ar g et ) .


MI , S I , ML, S L, DW , SDW or T

T his is t h e ad d r ess of t h e r eg is t er c on t a i n i n g t h e va l u e in th e mas t er P LC (s ourc e) . T h is va l u e w i l l b e wr i t t en i n t o th e s l ave 's r eg is t er , t h e r eg is t er t h at is t o b e p r es et .

Pr es et : V ec t or L en gt h


T h e l en gt h of th e vec t or of r eg is t ers i n b ot h mas t er an d s l ave. N ot e � A MOD BUS c omman d c ann ot r e ad mor e t h an 1 24 16-b i t in t eg ers , 6 2 d ou b l e r eg is t ers , or 6 4 f l oat r eg is t ers a t on e t i me. I n ad d i t i on , 0 is n ot a l eg al l en gt h. � I f , w i t h in t h e S l a ve: S t ar t of V ec t or p ar amet er , t h e s el ec t ed r eg is t er t yp e is a 32- b i t d ou b l e r eg is t er (s l av e

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ad dr ess es 5 1 00 an d gr e at er ) t h e p r es et vec t or l en gt h mus t b e d ou bl ed as wel l . I f , f or e xamp l e: - S l ave: S t ar t o f V ec t or p ar am et er is s et t o 6 30 0 , an d - You w ish t o pr es et 4 r eg is t ers , f or a t o t a l of 1 6 byt es - You mus t s et t h e P r es et V ec t or l en g th t o 8 . N ot e t h at th is mean s t h at , i n th es e c as es , t h e Pr es et : V ec t or L en g t h p ar am et er w i l l a l wa ys b e an e ven n u m b er .

S t at us MI Sh ows an er r or mess ag e n u mb er . T o d i ag n os e th e er r or , ch ec k th e MODBU S Er r or T abl e.



Configuring a MODBUS slave device The Ladder section below shows what elements are necessary to enable a master device to read from a slave. Note that the MODBUS Scan operation should not be performed during the initial program scan.

Note that you must use a condition (RLO) to activate the MODBUS Configuration.

The slave PLC Ladder application must include the elements shown below.

Step 1: Initializing the Ethernet card and configuring MODBUS

Note that all slave devices must be assigned ID number 255.

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Step 2: Scan

To enable the master PLC to access the slave, include a MODBUS Scan FB in the slave's application.

Slave Addressing Slave Address Tables Coils MOD BUS C omman d N u mb er

P oin t er V alu e Fr om:

Op er an d t yp e

R ead W r i t e

00 0 0 MB #1 5 F orc e C oi ls

30 0 0 SB #1 5 F orc e C oi ls

40 0 0 I ( r e ad -on l y)

# 0 1 R e ad C oi ls

R ead - on l y

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50 0 0 O #1 5 F orc e C oi ls

60 0 0 T ( r ead-on l y)

R ead - on l y

70 0 0 C( r ead -on l y)

R ead - on l y

R egis t ers MOD BUS C omman d N u mb er

P oin t er V al u e Fr om:

Op er an d t yp e

R egis t er s ize

R ead W r i t e

00 0 0 MI 16 b i t

40 0 0 S I 16 b i t

51 0 0 ML 32 b i t

61 0 0 SL 32 b i t

63 0 0 MDW 32 b i t

67 0 0 SDW 32 b i t

69 0 0 T imer pr es et

32 b i t

72 0 0 T imer cur r en t

32 b i t

75 0 0 C oun t er 16 b i t

77 0 0 MF 0 32 b i t

# 0 3 R e ad H old in g R egis t ers

# 1 6 P r es et H ol d i n g R egis t ers

Examples

The examples below show that: MODBUS addressing systems start at 1. Vision addressing start at 0.

Bit Operands

Read a 10-bit vector of inputs in a slave Vision controller, starting at Input 20, via Read Coils ( MODBUS COMMAND #1)

Vision PLC as the MODBUS master

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In VisiLogic's Read Coils FB, set the Slave: Start of Vector parameter to 4020, and the Read: Vector Length parameter to 10. Within the slave Vision controller, VisiLogic will read I 20 - I 29. SCADA as the MODBUS master

In the SCADA application, set the Slave: Start of Vector parameter to 34021(30001 + 4000 + 20), and the Read: Vector Length to 10, enabling the Master device to read I 20 - I 29 within the slave Vision controller.

Write a 3-bit vector of outputs in a slave Vision controller, starting at Output 8, via Force Coils (MODBUS COMMAND #15)

Vision PLC as the MODBUS master In VisiLogic's Force Coils FB, set the Slave: Start of Vector parameter to 5008, and the Read: Vector Length parameter to 3. Within the slave Vision controller, VisiLogic will write to O 8 - O 10. SCADA as the MODBUS master

In the SCADA application, set the Slave: Start of Vector parameter to 35009 (30001 + 5000 + 8) and the Read: Vector Length parameter to 3, enabling the Master device to write to O 8 - O 10 within the slave Vision controller.

Registers

Read a 9-register long vector of 16-bit integers in a slave Vision controller, starting at MI 32, via Read Holding Registers (MODBUS COMMAND #03)

Vision PLC as the MODBUS master In VisiLogic's Read Holding Registers FB, set the Slave: Start of Vector parameter to 32, and the Read: Vector Length parameter to 9. Within the slave Vision controller, VisiLogic will read MI 32 - MI 41.

SCADA as the MODBUS master In the SCADA application, set the Slave: Start of Vector parameter to 40033 (40001 + 0000 + 3), and the Read: Vector Length parameter to 9, enabling the Master device to read MI 32 - MI 41 within the slave Vision controller.

Note � If, within the Slave: Start of Vector parameter, the selected register type is a 32-bit double register (slave addresses 5100 and greater)the preset vector length must be doubled as well. If, for example in the VisiLogic Preset Holding Registers FB:

Slave: Start of Vector parameter is set to 6300, and You wish to preset 4 registers, for a total of 16 bytes You must set the Preset Vector length to 8.

Note that this means that, in these cases, the Preset: Vector Length parameter will always be an even number.

Read a 9-register long vector of 32 -bit integers in a slave Vision controller, starting at SL 32, via Preset Holding Registers (MODBUS COMMAND #16)

Vision PLC as the MODBUS master In VisiLogic's Preset Holding Registers FB, set the Slave: Preset Vector parameter to 6132, and the Read: Vector Length parameter to 18 ( 2x9, in order to fit the 32-bit SL registers ). Within the slave Vision controller, VisiLogic will read SL 32 - SL 41.

SCADA as the MODBUS master In the SCADA application, set the Slave: Start of Vector parameter to 406133,

MODBUS IP

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and the Read: Vector Length parameter to 18, enabling the Master device to read SL 32 - SL 41 within the slave Vision controller.

Write a 6-register long vector of 16-bit integers in a slave Vision controller, starting at MI 32, via Preset Holding Registers (MODBUS COMMAND #16)

Vision PLC as the MODBUS master In VisiLogic's Preset Holding Registers FB, set the Slave: Start of Vector parameter to 32, and the Preset: Vector Length parameter to 6. Within the slave Vision controller, VisiLogic will write to MI 32 - MI 37.

SCADA as the MODBUS master In the SCADA application, set the Slave: Start of Vector parameter to 40033, and the Read: Vector Length parameter to 6,enabling the Master device to write to MI 32 - MI 37 within the slave Vision controller.

MODBUS Error Table

Error # Error Message

0 N o Er r ors

1 I l l eg al F u nc t i on

2 I l l eg al D at a Ad dr ess

3 I l l eg al D at a V al u e

4 Mas t er - -T i me Ou t

5 N o C ommu nic at i on

6 Mis matc h ed U ni t ID

7 Mis matc h ed C omman d

8 Lengt h of mess ag e

9 Fu nc t i on n ot s u p p or t ed

10 I l l eg al f or mat

11 Mis matc h ed r ec ei ved d at a

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Index C communication ........................................ 10 M MODBUS .......................................... 10, 26

N network ..............................................10, 26

Documents

MODBUS IP - Elmarksupport.elmark.com.pl/unitronics/PDF/MODBUS_IP.pdf · model number. In addition, note that the Ethernet port is an RJ-45-type port that is lined with metal. Unitronics