Maxx GW4101

The device

The programmable maxx GW4101 mobile communication gateway for industrial applications collects and processes the information from your devices, machines and sensors, and transmits it via the expanded LTE network.

The basic unit (left part of the device) is described under maxx GW4100

The sensor interface expansion enhances the basic unit with interfaces for PT100/1000 temperature sensors and the widely used 4 – 20 mA current loop interface, as well as other digital inputs and outputs. The maxx GW4101 gateway is therefore ideal for transmitting measurements from the field to the head office or the cloud.

Interfaces

Pinout RS485 isolated

Description	Function	Label	Pin	Pin	Label	Function
#RS485	---	---	1	2	D+	IN D+
	ISO GND	IG	3	4	D-	IN D-

Pinout Digital IN/OUT

"Label" describes the labeling on the frontplate

"Signal" describes the reference to the Linux mapping

Description	Function	Label	Signal	Pin	Pin	Signal	Label	Function
#Isolated outputs	OUT 1	1A	ISO_OUT_A1	1	2	ISO_OUT_B1	1B	OUT 1
	OUT 2	2A	ISO_OUT_A2	3	4	ISO_OUT_B2	2B	OUT 2
#Isolated inputs	Iso Input 1-	1-	ISO_IN_N1	5	6	ISO_IN_P1	1+	iso Input 1+
	Iso Input 2-	2-	ISO_IN_N2	7	8	ISO_IN_P2	2+	iso Input 2+
	Iso Input 3-	3-	ISO_IN_N3	9	10	ISO_IN_P3	3+	iso Input 3+
	Iso Input 4-	4-	ISO_IN_N4	11	12	ISO_IN_P4	4+	iso Input 4+
#Digital inputs	GND	GND	GND	13	14	GND	GND	GND
	Digital Input 1	I1	GPIN1	15	16	GPIN2	I2	Digtal Input 2
	Digital Input 3	I3	GPIN3	17	18	GPIN4	I4	Digtal Input 4

Pinout 4-20mA IN/OUT

Description	Function	Label	Signal	Pin	Pin	Signal	Label	Function
#4-20mA current loop output	Current Loop Output	0+	OUT +	1	2	GND	GND	GND
#4-20mA current loop inputs	Current Loop Input 2	2+	IN_P2	3	4	IN_P3	3+	Current Loop Input 3
		2-	IN_N2	5	6	IN_N3	3-
	GND	GND	GND	7	8	GND	GND	GND
	Current Loop Input 4	4+	IN_P4	9	10	IN_P1	1+	Current Loop Input 1
		4-	IN_N4	11	12	IN_N1	1-
	GND	GND	GND	13	14	GND	GND	GND

Pinout RTD

Description	Function	Label	Signal	Pin	Pin	Signal	Label	Function
		--	NC	1	2	NC	--
#RTD	RTD 1 (A)	1A	RTD_A1	3	4	RTD_B1	1B	RTD 1 (B)
	RTD 2 (A)	2A	RTD_A2	5	6	RTD_B2	2B	RTD 2 (B)
	RTD 3 (A)	3A	RTD_A3	7	8	RTD_B3	3B	RTD 3 (B)
	RTD 4 (A)	4A	RTD_A4	9	10	RTD_B4	4B	RTD 4 (B) RS485 An isolated RS485 interface is available as /dev/ttymxc1. The interface includes a switchable termination resistor. The termination resistor is enabled by driving RS485_TERM_EN high. Analog inputs The GW4101 offers connection options for up to four resistive thermal devices (RTD, e.g. PT100/PT1000) and up to four 4-20mA current loop inputs. Internally an Texas Instruments ADS1220 16-bit ADC ist used. On the Linux side the ADC is accessible via SPI bus. The cost effective measurement circuit uses a single ADC which is multiplexed to the different measurement channel. To select a channel as well for RTD as also for loop current measurement the channel number (0-3) has to be written to RTDSEL[1..0]. RTD The following picture shows a simplified schematic of the ratiometric measurement circuit to determine the actual resistive value of the RTD devices. 4-20mA current loop inputs The measurement of the four loop currents is done one channel at a time by the means of a shunt resistor. The GW4101 provides a per channel current limited (30mA) 24V power supply for easy connection of external sensors. 4-20mA current loop output The device features a 4-20mA current loop output with integrated loop supply voltage. It is internally realized using a Microchip MCP4716 10-bit ADC with I2C interface. The following diagram shows the internal architecture of this output. Digital inputs The following diagram shows the internal design of the four digital inputs: This design allows the connection of push-pull- and open-collector-outputs with a threshold of about 4.5V. It is also possible to use a mechanical switch or a relais to connect the input to GND without the need for an additional pullup resistor. Following diagram shows a simplified design: Isolated inputs The following picture shows the simplified architecture one of the four isolated inputs with internal current limit and temperature stabilized threshold. Internally the isolation is achieved by the use of a TLP293 optocoupler. Isolated outputs The device contains a Panasonic AQW282 solid state relais to realize two independent isolated outputs. As there is no internal current limitation the user is responsible for ensuring a current flow of max. 300mA. Linux mapping Digital and analog I/Os (deprecated sysfs mapping) Signal Linux mapping Typ ISO_OUT1 /sys/class/gpio178 isolated digital outputs ISO_OUT2 /sys/class/gpio173 ISO_IN1 /sys/class/gpio176 isolated digital inputs ISO_IN2 /sys/class/gpio174 ISO_IN3 /sys/class/gpio172 ISO_IN4 /sys/class/gpio177 GPIN1 /sys/class/gpio197 digital inputs GPIN2 /sys/class/gpio203 GPIN3 /sys/class/gpio194 GPIN4 /sys/class/gpio197 digital inputs RS485_TERM_EN /sys/class/gpio175 RS485 termination resisitor RTDSEL1 /sys/class/gpio205 analog channel select RTDSEL2 /sys/class/gpio202 ADC_DRDY_n /sys/class/gpio206 ADC IRQ Digital and analog I/Os (new libgpiod mapping) Signal Linux mapping line Typ ISO_OUT1 gpiochips5 line 18 isolated digital outputs ISO_OUT2 gpiochip5 line 13 ISO_IN1 gpiochip5 line 16 isolated digital inputs ISO_IN2 gpiochip5 line 14 ISO_IN3 gpiochip5 line 12 ISO_IN4 gpiochip5 line 17 GPIN1 gpiochip6 line 5 digital inputs GPIN2 gpiochip6 line 11 GPIN3 gpiochip6 line 2 GPIN4 gpiochip6 line 6 RS485_TERM_EN gpiochip5 line 15 RS485 termination resisitor RTDSEL1 gpiochip6 line 13 analog channel select RTDSEL2 gpiochip6 line 10 ADC_DRDY_n gpiochip6 line 14 ADC IRQ Serial interfaces and busses Interface or bus Linux mapping isolated RS485 /dev/ttymxc1 SPI /dev/spidev2.0 ADS1220 I²C /dev/i2c-3 MCP4716