WB-MAI11 Modbus Analog Inputs/en

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WB-MAI, side view

Purpose

The analog input module is designed for:

• voltage measurement;
• current measurement;
• resistance measurements on two-wire and three-wire circuits;
• temperature measurements using thermocouples or resistance thermometers;
• signal measurements from ratiometric sensors or variable resistors;
• connection of dry contact and open collector type signals.

The input mode is selected when configuring the instrument. No additional external load/pull-up resistors are required. The device allows you to connect up to 22 different sensors at the same time.

Design: housing on DIN-rail (width 6 units). Supply voltage 12 – 24V.

The module is controlled from the controller or PC via RS-485 bus by Modbus commands.

Specifications

Table 1. Technical parameters.

Parameter	Value
Power
Supply voltage	12 V – 24 V
measurement Channels
Number of channels	11 differential or 22 normal
Voltage measurement	-5 – 5 V differential mode 0 – 5 V normal operation
Current measurement	0 – 20 mA
Resistance measurement	0 – 5000 Ohms
Types of thermocouples supported	K
Types of resistance thermometers supported	Rt50, Pt100, Pt500, Pt1000, 50P, 100P, 500P, 1000P, 50M, 100M, 500M, 1000M, Ni100, Ni500, NI1000
Voltage measurement error	±0.2%
Current measurement error	±0.2%
Error in the measurement of resistance	±0.1% for INxP inputs ±1% for INxN inputs ±(0.1% + 0.003·Rw) for three-wire circuit
Control
Management interface	RS-485
Interface isolation	Galvanically isolated from measuring circuits
Communication protocol	Modbus RTU, address is set by software, factory settings are indicated on the label
RS-485 interface parameters	Default speed of 9600 bps; data bits 8; parity N; stop bits 2. Interface parameters can be configured programmatically: Speed: 1200, 2400, 4800, 9600 (default), 19200, 38400, 57600, 115200 bit/s (configure RS-485 communication parameters for Wiren Board Modbus devices) Data: 8 bit Parity check: none (default), 1 - odd (odd), 2 - even (even) Stop bits: 1, 2 (default)
Ready for operation after power supply	1 c
dimensions
Size	106.25 x 90.2 x 57.5 mm
operating Conditions
Air temperature
Relative humidity	up to 98%, without condensation

Connection diagrams

The module is made in a plastic case and is designed for installation in a mounting box on a DIN rail.

Fig. 1 shows the connection diagram of the sensor with the output type "voltage" in differential mode. This scheme is suitable for sensors whose output voltage can take negative values. Allows you to measure voltages from -5 to 5 V.

Fig. 2 shows the voltage measurement circuit relative to the common wire. This scheme allows you to measure only positive voltages from 0 to 5 V. It is possible to connect two sensors to one input. Fig.3 shows the connection diagram of sensors with a current output of 0-20 mA (4-20 mA). Load resistors with a nominal value of 100 Ω built in the device and connect via the software, the configuration process of the device. It is possible to connect two sensors to one input. Fig. 4 shows the K-type thermocouple connection diagram. For correct detection of the absence of thermocouple input filter capacitors are discharged short-term (several µs) pulses with built-in resistors 100 Ohms. It is necessary to keep this in mind, if you connect another source of EMF instead of a thermocouple. The capacitors are only discharged in the "Standard sensors" mode when one of the supported thermocouples is selected. In basic modes, no discharge is performed. For rice. 5 shows the connection diagram of the sensors of the dry contact or resistance measurement on a two-wire circuit (shown by the dotted line). When using a two-wire circuit, the resistance of the wires is included in the measurement result. Due to the internal features of the INxP input device, the accuracy of the resistance measurement is greater than that of the INxN inputs. This should be taken into account when connecting the sensors. It is possible to connect two sensors to one input. Fig. 6 is the scheme of connection of ratiometric sensors or variable resistors. In this mode, the signal from the sensor is measured as a percentage - from 0% (GND level) to 100% (+5V level). It is possible to connect two sensors to one input. Fig. 7 shows a diagram of the resistance measurement of the three-wire circuit. In this mode, the resistance of the wires has almost no effect on the measurement result, provided that all the wires to the sensor are the same. The absolute effect of wire resistance on the final result is 0.003 Rw as opposed to 2Rw (Rw is the resistance of one wire to the sensor) in a two-wire circuit. Fig. 8 shows a diagram of the resistance measurement using the current measurement. This circuit is used to connect an NTC thermistor. In this mode, the device can measure resistance in a wide range - from 150 Ohms to 1 MW. But keep in mind that the lower the resistance of the NTC, the greater the current in the circuit and self-heating NTC (as opposed to the circuits in Fig. 5 and Fig.7, where the current in the circuit is constant regardless of resistance). Therefore, the device artificially reduces the input polling rate depending on the current NTC resistance to compensate for self-heating. It is possible to connect two NTC to one input, but in this case, the polling rate is reduced, because during the survey of one, the current goes through both NTC, which leads to an increase in idle time to compensate for self-heating. To improve the accuracy of high resistance measurements, it is recommended to select the lowest possible data rate - 20 SPS.

Possible combinations of sensors to a single login

Two sensors can be connected to the same input with the following restrictions:

• If the channel INxP / off, channel, INxN should also be turned off
• If the channel INxP has a differential type configuration for channel INxN ignored
• Channel INxN may not have a differential type
• If the INxP channel is set to current measurement mode, the INxN channel must also be set to current measurement or disabled
• If the INxP channel is set to resistance or voltage measurement mode, the INxN channel must also be set to resistance or voltage measurement
• If the channel is configured to INxP mode of resistance measurement using the current measurement, and the channel INxN also have this mode or turned off

Channel settings INxP override the channel settings INxN. If the above conditions are not met, the INxN channel settings are ignored and the channel is disabled. Table 2 shows the possible sensor combinations for a single input.

Table 2. Possible combinations of sensors to one input.

inxp channel connection Diagram	Possible inxn circuit
	Figure 1	Figure 2	Figure 3	Figure 4	Figure 5	Figure 6	Figure 7	Figure 8
Figure 1 The measurement of the voltage in differential mode
Figure 2 Voltage measurement		V			V	V
Figure 3 Current measurement			V
Figure 4 The connection of the thermocouple
Figure 5 Connection of "dry contact" sensors and resistance measurement according to two-wire scheme		V			V	V
Figure 6 Connection of ratiometric sensors		V			V	V
Figure 7 Resistance measurement by three-wire circuit
Figure 8 Resistance measurement using the current measurement								V

Description of Modbus registers

All modbus registers of the device are divided into 3 groups:

• Device settings
• The setting of the measurement channels
• Measured value

The register map is shown in table 3. 'X' in the register address is the entry number from 1 to 11 (0x1 to 0xB).

Table 3. Description of Modbus control registers.

Hex address	Dec address	Type	Read-write	Default	Format	Purpose
Device parameters
0x006E	110	holding	RW	96	baud rate / 100	RS-485 port speed, divided by 100. Allowable speed: 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200
0x006F	111	holding	RW	0	0, 1, 2	Configure the RS-485 port parity bit. Valid values: 0 - no parity bit (none), 1 - odd (odd), 2 - even (even)
0x0070	112	holding	RW	2	1, 2	Number of stop bits of RS-485 port. Valid values: 1, 2
0x0078	120	holding	RW	0	otрук than 0	Restart. Writing to the register causes the module restart without saving state
0x0080	128	holding	RW	1		Device Modbus-address
0x00C8 - 0x00CE	200 - 206	input	R	{'M','A','I',0,0,0}		Signature
0x00DC - 0x00F1	220 - 241	input	R		__date__ __time__	Firmware build date
0x00FA - 0x010D	250 - 269	input	R		string, null-terminated	Firmware version
0x010A - 0x010F	266 - 271	input	R			Unique identifier(S/N)
The setting of the measurement channels
0xX400	4096·X + 1024	holding	RW	0	Тable 4, table 5	Type of sensor connected to INxP channel or to INx in differential mode (see tables 4 and 5)
0xX401	4096·X + 1025	holding	RW	0	Table 4, table 5	Type of sensor connected to the INxN channel (see tables 4 and 5)
0xX402	4096·X + 1026	holding	RW	0	0, 20, 45, 90, 175, 330, 600, 1000	Data rate for INxP or INx channels in differential mode, SPS. 0 - channel is off
0xX403	4096·X + 1027	holding	RW	0	0, 20, 45, 90, 175, 330, 600, 1000	Data rate for INxN channels, SPS. 0 - channel off
0xX404	4096·X + 1028	holding	RW	0	0 - 50	Number of continuous measurements for INxP or INx channels in differential mode
0xX405	4096·X + 1029	holding	RW	0	0 - 50	Number of continuous measurements for INxN channels
0xX406	4096·X + 1030	holding	RW	0	0 - 65000	Characteristic time of lowpass filter for INxP or INx channels in differential mode, ms
0xX407	4096·X + 1031	holding	RW	0	0 - 65000	The characteristic time lowpass filter for INxN channels, ms
0xX408	4096·X + 1032	holding	RW	0	16-bit signed int	The lower limit of the measuring range of the active sensor channels INx INxP or in differential mode
0xX409	4096·X + 1033	holding	RW	0	16-bit signed int	The lower limit of the measuring range of the active sensor for INxN channels
0xX40A	4096·X + 1034	holding	RW	1000	16-bit signed int	The upper limit of the measuring range of the active sensor channels INx or INxP in differential mode
0xX40B	4096·X + 1035	holding	RW	1000	16-bit signed int	The upper limit of the measuring range of the active sensor INxN channels
0xX40C	4096·X + 1036	holding	RW	0	0 (авто), 1, 2, 4, 8, 16, 32, 64, 128	Gain factor for INxP or INx channels in differential mode
0xX40D	4096·X + 1037	holding	RW	0	0 (авто), 1, 2, 4, 8, 16, 32, 64, 128	The gain factor for INxN channels
Measured values
0xX500	4096·X + 1280	input	R	0	32-bit signed int	Measured value for inxp or differential INX channel
0xX502	4096·X + 1282	input	R	0	32-bit signed int	The measured value for INxN channel
0xX504	4096·X + 1284	input	R	0	16-bit signed int	Converted to physical quantity value for inxp channel or differential INx channel
0xX505	4096·X + 1285	input	R	0	16-bit signed int	Converted into physical quantity value for channel INxN
0xX506	4096·X + 1286	input	R	1	16-bit signed int	The current gain factor for channel INxP or differential channels INx
0xX507	4096·X + 1287	input	R	1	16-bit signed int	The current gain factor for channel INxN
0x0600	1536	input	R	0	16-bit signed int	Terminal voltage +5V, мВ
0x0601	1537	input	R	0	16-bit signed int	Temperature inside the device, °C·100

Since each input supports and differential (scheme in Fig. 1,4,7) and normal mode (scheme in Fig. 2,3,5,6) operation, the sensor type is set for inxp and INxN inputs separately in the respective registers 0xX400 и 0xX401, where X is the input number from 1 to 11 in hexadecimal (0x1 to 0xB).

If the channel is set to automatic gain factor, the channel polling rate may be reduced by requiring multiple measurements to match the gain factor.

Only gain factors 1, 2 and 4 are available for normal channel operation.

If the differential mode was set for INxP input, the values of the configuration register INxN inputs are ignored. Only normal mode can be installed for inputs INxN.

Description of device operation modes

The device allows you to configure the following operating modes for each input:

• Voltage measurement relative to +5V (in differential or normal mode)
• Voltage measurement (differential or normal mode)
• Resistance measurement (in differential or normal mode)
• Current measurement (normal mode only)
• Resistance measurement via current measurement (normal mode only)

Table 4 provides a complete description of all possible operating modes. These modes are "basic", the measurement of signals from standard sensors is based on them.

The registers "sensor type" (0xX400, 0xX401) for each input can store codes from table 4 or from table 5. To measure non-standard values, you can select the input type and the measurement range manually from table 4.

Table 4. Description of the device operation modes.

Measurable type signal	Input mode	Code HEX	Code DEC	Description	Gain factor	Measuring range	Error	Output format of data
Voltage measurement relative to +5V	Normal	0x0000	0	Voltage measurement from ratiometric sensors (diagram in Fig.6) Voltage measurement from 0 to 5V (diagram in Fig.2)	1	0...(+5V)	±0.1%	% · 100
					2	0...(+5V / 2)
					4	0...(+5V / 4)
	Differential	0x0100	256	differential voltage Measurement from -5 to 5 V (diagram in Fig. 1)	1	± (+5V)	±0.1%
					2	± (+5V / 2)
					4	± (+5V / 4)
Measurement voltages	Normal	0x0001	1	Normal voltage measurement from 0 to 2 V (diagram in Fig.2)	1	0...2048 MB	±0.2%	mV · 100
					2	0...1024 MB
					4	0...512 MB
	Differential	0x0101	257	differential voltage Measurement from -2 V to 2 V (diagram in Fig.1) Measuring the voltage from a thermocouple (diagram in Fig.4)	1	± 2048 mV	±0.2%
					2	± 1024 mV
					4	± 512 mV
					8	± 256 mV	±0.25%
					16	± 128 mV
					32	± 64 mV
					64	± 32 mV
					128	± 16 mV
Resistance measurement	Normal for INxP inputs	0x0002	2	Resistance measurement using two-wire circuit (diagram in Fig.5) Connection of sensors of dry contact type (diagram in Fig.5)	1	0...5000 Ohms	±0.1%	Ohm · 100
					2	0...2550 Ohms
					4	0...1275 Ohms
	Normal for INxN inputs				1	0...5100 Ohms	±1% nominal ±6% max
					2	0...2550 Ohms
					4	0...1275 Ohms
	Differential (three-wire circuit)	0x0102	258	Three-wire resistance measurement (diagram in Fig. 7)	1	0...5000 Ohms	±0.1%
					2	0...2550 Ohms
					4	0...1275 Ohms
Currents measurement	Normal	0x0003	3	Current measurement from 0 to 20 mA (diagram in Fig.3)	1	0...20.48 mA	±0.2%	mA · 10000
					2	0...10.24 mA
					4	0...5.12 mA
Resistance measurement through measurement of the current in the circuit	Normal	0x0004	4	NTC thermistor resistance measurement (diagram in Fig. Eight) The current in the circuit is only at the time of polling the current input, during the polling of other inputs current absents, unlike the "current measurement" mode, where the current is always on.	1	200 Ohms .. 250 ohms	±3% at end of range ±1.5% in the middle of the range ±0.5% at the beginning of the range	Ohm
					2	500 Ohms .. 500 kOhm
					4	1200 Ohms .. 1 Mω

Types of supported standard sensors

The supported types of standard sensors are shown in table 5. When using standard sensors, the values of registers 0xX40A and 0xX40B (gain) are ignored. Standard sensors have code 0x1XXX.

Table 5. Types of standard sensors

Sensor code HEX	Sensor code DEC	Description	Coefficient gains	Format raw data	Format recalculated data	Error
Thermoelectric converters Mode of operation – measuring the voltage from the thermocouple (diagram in Fig. Four)
0x1000	4096	THA (K)	32	mV · 100	°C · 10	±0.5 °C
two-wire resistance Thermometers Mode of operation – resistance measurement on a two-wire scheme (scheme in Fig. Five)
0x1100	4352	Pt 50 (α = 0.00385 °C -1)	4	Ohm · 100	°C · 10	±0.4 °C
0x1101	4353	Pt 100 (α = 0.00385 °C -1)	4
0x1102	4354	Pt 500 (α = 0.00385 °C -1)	2			±0.25 °C
0x1103	4355	Pt 1000 (α = 0,00385 °C -1)	1
0x1110	4368	50P (α = 0.00391 °C -1)	4			±0.4 °C
0x1111	4369	100P (α = 0.00391 °C -1)	4
0x1112	4370	500P (α = 0.00391 °C -1)	2			±0.25 °C
0x1113	4371	1000P (α = 0.00391 °C -1)	1
0x1120	4384	50M (α = 0.00428 °C -1)	4			±0.35 °C
0x1121	4385	100M (α = 0.00428 °C -1)	4
0x1122	4386	500M (α = 0.00428 °C -1)	4			±0.25 °C
0x1123	4387	1000M (α = 0,00428 °C -1)	2
0x1130	The 4400	Ni 100 (α = 0,00617 °C -1)	4
0x1131	4401	Ni 500 (α = 0,00617 °C -1)	2			±0.2 °C
0x1132	4402	Ni 1000 (α = 0,00617 °C -1)	1
three-wire resistance Thermometers Mode of operation – resistance measurement on a three-wire scheme (scheme in Fig. Seven)
0x1200	4608	Pt 50 (α = 0.00385 °C -1)	4	Ohm · 100	°C · 10	±0.4 °C
0x1201	4609	Pt 100 (α = 0.00385 °C -1)	4
0x1202	4610	Pt 500 (α = 0.00385 °C -1)	2			±0.25 °C
0x1203	4611	Pt 1000 (α = 0,00385 °C -1)	1
0x1210	4624	50P (α = 0.00391 °C -1)	4			±0.4 °C
0x1211	4625	100P (α = 0.00391 °C -1)	4
0x1212	4626	500P (α = 0.00391 °C -1)	2			±0.25 °C
0x1213	4627	1000P (α = 0.00391 °C -1)	1
0x1220	4640	50M (α = 0.00428 °C -1)	4			±0.35 °C
0x1221	4641	100M (α = 0.00428 °C -1)	4
0x1222	4642	500M (α = 0.00428 °C -1)	4			±0.25 °C
0x1223	4643	1000M (α = 0,00428 °C -1)	2
0x1230	4656	Ni 100 (α = 0,00617 °C -1)	4
0x1231	4657	Ni 500 (α = 0,00617 °C -1)	2			±0.2 °C
0x1232	4658	Ni 1000 (α = 0,00617 °C -1)	1
Current output sensors Operating mode – current measurement from 0 to 20 mA (diagram in Fig. Three)
0x1300	4864	0 to 5 mA	4	mA · 10000	0 mA = lower bound (registers 0xX408 / 0xX409) 5 mA = upper bound (registers 0xX40A / 0xX40B)	±0.25 %
0x1301	4865	0 to 20 mA	1	mA · 10000	0 mA = lower bound (registers 0xX408 / 0xX409) 20 mA = upper bound (registers 0xX40A / 0xX40B)	±0.25 %
0x1302	4866	from 4 to 20 mA	1	mA · 10000	4 mA = lower bound (registers 0xX408 / 0xX409) 20 mA = upper bound (registers 0xX40A / 0xX40B)	±0.25 %
Sensors with voltage output in normal mode Operating mode – voltage measurement in normal mode from 0 to 2 V (diagram in Fig. Two)
0x1400	5120	0 to 1 V	2	mV · 100	0 V = lower bound(registers 0xX408 / 0xX409) 1 V = upper bound (registers 0xX40A / 0xX40B)	±0.2 %
Sensors with voltage output in differential mode Operating mode – voltage measurement in differential mode from -2 to 2 V (diagram in Fig. One)
0x1500	5376
32	mV · 100	-50 mV = lower bound(registers 0xX408 / 0xX409) 50 mV = upper bound (registers 0xX40A / 0xX40B)	±0.2 %
Contact sensors (dry) Mode of operation – resistance measurement on a two-wire scheme (scheme in Fig. Five)
0x1600	5632	Dry contact	1	Ohm · 100	0 - sensor open or missing 1 - sensor closed
NTC thermistors Mode of operation - resistance measurement through current measurement (diagram in Fig. Eight)
0x1700	5888	NTC 10k (B = 3988 K)	1 - 4 (auto)	Ohm	°C · 10	Below-40 °C: ±1 °C -40 to -20 °C: ±0.5 °C Above -20 °C: ±0.25 °C

Device configuration examples

Table 6 shows some examples of device configuration. Register addresses are given for channel 1. To use other channels, the addresses should be recalculated according to table 3.

В таблице заполнены только те ячейки, которые влияют на конфигурацию входа для измерения сигналов с указанных датчиков. В остальные регистры конфигурации следует записать "0".

Таблица 6. Примеры конфигурации устройства.

Адрес регистра	Примеры конфигураций для некоторых датчиков
	Измерение температуры термопарой K-типа (подключена к входу IN1). Схема на рис. 4	Измерение температуры термометров сопротивления Pt1000 по трехпроводной схеме (подключен к входу IN1). Схема на рис. 7	Измерение сигнала с датчика с токовым выходом 4-20 мА (подключен к входу IN1P). Схема на рис. 3	Измерение температуры NTC-термистором 10 кОм, B = 3988 K. Схема на рис. 8
Регистры конфигурации
0x1400	0x1000	0x1203	0x1302	0x1700
0x1401
0x1402	20	20	20	20
0x1403
0x1404	0	0	0	0
0x1405
0x1406			100
0x1407
0x1408			800
0x1409
0x140A
0x140B
Регистры измеренных значений
0x1500	Напряжение на термопаре, мВ · 100	Сопротивление датчика, Ом · 100	Ток, мА · 10000	Сопротивление датчика, Ом
0x1502
0x1504	Температура спая, °C · 10	Температура датчика, °C · 10	100 - при токе 4 мА; 800 - при токе 20 мА если значение не в диапазоне [100..800], датчик неисправен или отсутствует	Температура датчкика, °C · 10
0x1505
0x1506
0x1507