Manufacturers of Custom and Standard Industrial Embedded Single-Board Computers


Modbus compatible Relay/opto Single-Board Computer

  • Modbus compatible
  • Wireless modem
  • 8 relays and opto inputs
  • 8-30V DC power in
  • 12V battery charger
  • 2 RS-232/485 serial ports
  • Operating system includes Basic for custom control
  • LED indicators
  • 2 Flow measurement pulse counters


The CX-10 is an intelligent relay single-board computer intended for remote monitoring and control of powered devices. Eight 125VAC relays can switch up to 2 amps each. Opto inputs monitor 12V levels. The CX-10 can operate independently running its own Basic program and/or operate as a modbus device on an RF or RS-485 network. A built in battery charger allows for remote operation with a solar panel acting as a power source. One RS-232 serial port is normally used for programming but can be connected to other devices, such as a display or pressure transducer. The second port, programmable as a modbus or ASCII port, communicates via RF modem, RS-232 or RS-485.

Two optically isolated pulse counter inputs count pulses from flow measurement devices.

Functional Description


Eight relays are divided into 3 groups. A common line supplies power to one group of 4 relays and two groups of two relays. This configuration will allow you to reverse a motor direction. Relays may switch up to 125VAC and 2 amperes each.

An LED lights up when a relay is energized.

Opto Input

Eight optically isolated inputs accept 5-16 VDC inputs. Opto inputs have a common ground. Two of the inputs support a pulse output.

When an opto input is energized, an LED lights up. LED’s may be turned off via Modbus register if power consumption is important. 

Flow Meter Pulse Counter

Two of the optically isolated inputs can also act as a pulse counter. Counters are read as a floating point number in the range of 0 to 16,000,000. Maximum pulse counting rate is 1000 pulses/second. Typically, a flow meter outputs 30 pulses/second.


The CX-10 can operate from a 8-24VDC power source. A battery may be attached to the CX-10 along with either a solar panel or line power supply. Power consumption will vary depending upon the number of relays energized and if an RF modem is attached. When all relays are off, no opto inputs are active, and the RF modem is not transmitting, power consumption is under 100 milli-amps. Each energized relay requires about 80 milli-amps. The RF modem may require over 1 ampere when transmitting. Usually, this is for short periods of time.

A 12V battery charger circuit is included on the CX-10. Float and charge levels may be set via modbus registers. Both battery and power input levels are read via modbus registers.


There are two ways the CX-10 can be programmed. One way is via modbus registers. Registers can turn relays on/off, read opto inputs, and a variety of other functions. Refer to the CX-10 manual for more information.

 The second way is by Basic program. The operating system contains a Basic-52 incremental line compiler. This is a fancy way of saying you can write a basic program on the board. The program has access to modbus registers and thus can control relays and monitor inputs. Basic also has floating point math and timers to allow you to perform either primary or fail-safe operations. 

Modbus run simultaneously with a Basic program. It is possible, for example, to set a register (or group of registers) via modbus and have the Basic program monitor and / or respond to a register. 


There are two serial ports on the CX-10. One of them is an RS-232 only port. It is used, generally, for programming. However, you may connect a serial display or other serial device to this port.  

The 2nd serial port is usually used for modbus. However, it can be programmed (via modbus register) for ASCII (non-modbus) mode. This serial port has 3 hardware ports: RS-232, RS-485, and RF modem. The configuration of the CX-10 allows simultaneous use of RS-485 and RF modem. Thus, you can connect multiple CX-10's using a single RF Modem. 

The RF Modem is a Digi International XT09 type device. It is a 900 Mhz spread spectrum radio with a maximum power output of 1 watt. Under ideal conditions, it can communicate over a mile.

Modbus Protocol

Control and data registers are read from and written to using Daniels modbus protocol. This version is similar to other Modbus protocols such as Enron modbus. When accessing registers, the address may have to be adjusted by 1. Unit ID, functions 3 and 16, and CRC are supported.

 In addition to 8 bit addressing, 16 bit modbus address is supported. To indicate 16 bit modbus addressing, we start every message with 255 and include an extra address byte in the data packet. 8 bit addressing allows 255 devices while 16 bit address allows over 65,000 devices to be connected on a network. Contact Remote Processing for more details.

More Information

Hardware  manual - for the CX-10 Single-Board Computer - in PDF format

Software manual - uses Basic-52 Programming Language for the CX-10