MODBUS.md

Modbus

The Industrial Automation I/O Expansion cards for Raspberry Pi can be accessed thru Modbus RTU protocol over RS-485 port. You can set-up the RS-485 port with megaind command.

Example:

~$ megaind 0 rs485wr 1 9600 1 0 1

Set Modbus RTU , Baudrate: 9600bps, 1 Stop Bit, parity: None, slave address offset: 1

~$ megaind -h rs485wr

display the full set of options

Slave Address

The slave address is add with the "stack level" jumpers. For example the jumpers configuration for stack level 1 (one jumper in position ID0) slave address offset to 1 corespond to slave address 2.

Modbus object types

All modbus RTU object type with standard addresses are implemented : Coils, Discrete Inputs, Input registers, Holding registers.

Coils

Acces level Read/Write, Size 1 bit

Device function	Register Address	Modbus Address
OPEN_DRAIN_1	0001	0x00
OPEN_DRAIN_2	0002	0x01
OPEN_DRAIN_3	0003	0x02
OPEN_DRAIN_4	0004	0x03
LED_1	0005	0x04
LED_2	0006	0x05
LED_3	0007	0x06
LED_4	0008	0x07
OPTO_RISING_COUNT_1	0009	0x08
OPTO_RISING_COUNT_2	0010	0x09
OPTO_RISING_COUNT_3	0011	0x0a
OPTO_RISING_COUNT_4	0012	0x0b
OPTO_FALLING_COUNT_1	0013	0x0c
OPTO_FALLING_COUNT_2	0014	0x0d
OPTO_FALLING_COUNT_3	0015	0x0e
OPTO_FALLING_COUNT_4	0016	0x0f

OPTO_RISING_COUNT coil enable/disable counting on rising edge of coresponding opto channel OPTO_FALLING_COUNT coil enable/disable counting on falling edge of coresponding opto channel

Discrete Inputs

Access level Read Only, Size 1 bit

Device function	Register Address	Modbus Address
OPTO_1	10001	0x00
OPTO_2	10002	0x01
OPTO_3	10003	0x02
OPTO_4	10004	0x03
OWB_PRESENT	10005	0x04

Input registers

Access level Read Only, Size 16 bits

Device function	Register Address	Description	Measurement Unit
0-10V_IN_1	30001	0-10V Input 1	mV
0-10V_IN_2	30002	0-10V Input 2	mV
0-10V_IN_3	30003	0-10V Input 3	mV
0-10V_IN_4	30004	0-10V Input 4	mV
+/-10V_IN_1	30005	+/-10V Input 1	mV
+/-10V_IN_2	30006	+/-10V Input 2	mV
+/-10V_IN_3	30007	+/-10V Input 3	mV
+/-10V_IN_4	30008	+/-10V Input 4	mV
4-20mA_IN_1	30009	4-20mA Input 1	uA
4-20mA_IN_2	30010	4-20mA Input 2	uA
4-20mA_IN_3	30011	4-20mA Input 3	uA
4-20mA_IN_4	30012	4-20mA Input 4	uA
OPTO_COUNT_1	30013	Opto Count 1
OPTO_COUNT_2	30014	Opto Count 2
OPTO_COUNT_3	30015	Opto Count 3
OPTO_COUNT_4	30016	Opto Count 4
OWB_TEMP1	30017	Temperature 1	0.01C
OWB_TEMP2	30018	Temperature 2	0.01C
OWB_TEMP3	30019	Temperature 3	0.01C
OWB_TEMP4	30020	Temperature 4	0.01C
OWB_TEMP5	30021	Temperature 5	0.01C
OWB_TEMP6	30022	Temperature 6	0.01C
OWB_TEMP7	30023	Temperature 7	0.01C
OWB_TEMP8	30024	Temperature 8	0.01C
OWB_TEMP9	30025	Temperature 9	0.01C
OWB_TEMP10	30026	Temperature 10	0.01C
OWB_TEMP11	30027	Temperature 11	0.01C
OWB_TEMP12	30028	Temperature 12	0.01C
OWB_TEMP13	30028	Temperature 13	0.01C
OWB_TEMP14	30030	Temperature 14	0.01C
OWB_TEMP15	30031	Temperature 15	0.01C
OWB_TEMP16	30032	Temperature 16	0.01C
OWB_ID_A_TEMP1	30033	ID A Temperature 1	64 bit ID
OWB_ID_B_TEMP1	30034	ID B Temperature 1
OWB_ID_C_TEMP1	30035	ID C Temperature 1
OWB_ID_D_TEMP1	30036	ID D Temperature 1
OWB_ID_A_TEMP2	30037	ID A Temperature 2	64 bit ID
OWB_ID_B_TEMP2	30038	ID B Temperature 2
OWB_ID_C_TEMP2	30039	ID C Temperature 2
OWB_ID_D_TEMP2	30040	ID D Temperature 2
OWB_ID_A_TEMP3	30041	ID A Temperature 3	64 bit ID
OWB_ID_B_TEMP3	30042	ID B Temperature 3
OWB_ID_C_TEMP3	30043	ID C Temperature 3
OWB_ID_D_TEMP3	30044	ID D Temperature 3
OWB_ID_A_TEMP4	30045	ID A Temperature 4	64 bit ID
OWB_ID_B_TEMP4	30046	ID B Temperature 4
OWB_ID_C_TEMP4	30047	ID C Temperature 4
OWB_ID_D_TEMP4	30048	ID D Temperature 4
OWB_ID_A_TEMP5	30049	ID A Temperature 5	64 bit ID
OWB_ID_B_TEMP5	30050	ID B Temperature 5
OWB_ID_C_TEMP5	30051	ID C Temperature 5
OWB_ID_D_TEMP5	30052	ID D Temperature 5
OWB_ID_A_TEMP6	30053	ID A Temperature 6	64 bit ID
OWB_ID_B_TEMP6	30054	ID B Temperature 6
OWB_ID_C_TEMP6	30055	ID C Temperature 6
OWB_ID_D_TEMP6	30056	ID D Temperature 6
OWB_ID_A_TEMP7	30057	ID A Temperature 7	64 bit ID
OWB_ID_B_TEMP7	30058	ID B Temperature 7
OWB_ID_C_TEMP7	30059	ID C Temperature 7
OWB_ID_D_TEMP7	30060	ID D Temperature 7
OWB_ID_A_TEMP8	30061	ID A Temperature 8	64 bit ID
OWB_ID_B_TEMP8	30062	ID B Temperature 8
OWB_ID_C_TEMP8	30063	ID C Temperature 8
OWB_ID_D_TEMP8	30064	ID D Temperature 8
OWB_ID_A_TEMP9	30065	ID A Temperature 9	64 bit ID
OWB_ID_B_TEMP9	30066	ID B Temperature 9
OWB_ID_C_TEMP9	30067	ID C Temperature 9
OWB_ID_D_TEMP9	30068	ID D Temperature 9
OWB_ID_A_TEMP10	30069	ID A Temperature 10	64 bit ID
OWB_ID_B_TEMP10	30070	ID B Temperature 10
OWB_ID_C_TEMP10	30071	ID C Temperature 10
OWB_ID_D_TEMP10	30072	ID D Temperature 10
OWB_ID_A_TEMP11	30073	ID A Temperature 11	64 bit ID
OWB_ID_B_TEMP11	30074	ID B Temperature 11
OWB_ID_C_TEMP11	30075	ID C Temperature 11
OWB_ID_D_TEMP11	30076	ID D Temperature 11
OWB_ID_A_TEMP12	30077	ID A Temperature 12	64 bit ID
OWB_ID_B_TEMP12	30078	ID B Temperature 12
OWB_ID_C_TEMP12	30079	ID C Temperature 12
OWB_ID_D_TEMP12	30080	ID D Temperature 12
OWB_ID_A_TEMP13	30081	ID A Temperature 13	64 bit ID
OWB_ID_B_TEMP13	30082	ID B Temperature 13
OWB_ID_C_TEMP13	30083	ID C Temperature 13
OWB_ID_D_TEMP13	30084	ID D Temperature 13
OWB_ID_A_TEMP14	30085	ID A Temperature 14	64 bit ID
OWB_ID_B_TEMP14	30086	ID B Temperature 14
OWB_ID_C_TEMP14	30087	ID C Temperature 14
OWB_ID_D_TEMP14	30088	ID D Temperature 14
OWB_ID_A_TEMP15	30089	ID A Temperature 15	64 bit ID
OWB_ID_B_TEMP15	30090	ID B Temperature 15
OWB_ID_C_TEMP15	30091	ID C Temperature 15
OWB_ID_D_TEMP15	30092	ID D Temperature 15
OWB_ID_A_TEMP16	30093	ID A Temperature 16	64 bit ID
OWB_ID_B_TEMP16	30094	ID B Temperature 16
OWB_ID_C_TEMP16	30095	ID C Temperature 16
OWB_ID_D_TEMP16	30096	ID D Temperature 16

Holding registers

Access level Read/Write, Size 16 bits

Device function	Register Address	Modbus Address	Measurement Unit	Range
0-10V_OUT_1	40001	0x00	mV	0..10000
0-10V_OUT_2	40002	0x01	mV	0..10000
0-10V_OUT_3	40003	0x02	mV	0..10000
0-10V_OUT_4	40004	0x03	mV	0..10000
4-20mA_OUT_1	40005	0x04	uA	4000..20000
4-20mA_OUT_2	40006	0x05	uA	4000..20000
4-20mA_OUT_3	40007	0x06	uA	4000..20000
4-20mA_OUT_4	40008	0x07	uA	4000..20000
OPEN_DRAIN_PWM_1	40009	0x08		0..10000
OPEN_DRAIN_PWM_2	40010	0x09		0..10000
OPEN_DRAIN_PWM_3	40011	0x0a		0..10000
OPEN_DRAIN_PWM_4	40012	0x0b		0..10000

Function codes implemented

• Read Coils (0x01)
• Read Discrete Inputs (0x02)
• Read Holding Registers (0x03)
• Read Input Registers (0x04)
• Write Single Coil (0x05)
• Write Single Register (0x06)
• Write Multiple Coils (0x0f)
• Write Multiple registers (0x10)