Communication Technology by: Semitech Semiconductor. SM2400 Serial-2-PLC Adapter User s Guide

Transcription

1 Communication Technology by: Semitech Semiconductor Serial-2-PLC Adapter User s Guide

2 This publication contains proprietary information which is subject to change without notice and is supplied as is, without any warranty of any kind. Revision History Revision Number Date Tasks A 02/2019 Serial-2-PLC Adapter User s Guide initial release. EVK User s Guide 2

3 Table of Contents 1. Introduction Features Hardware Connection Evaluate ASCII Pass-through Using the Replacing the Bus with Power Line via - with ASCII Pass-through ASCII Pass-through Configurations Supported AT Commands Supported AT Registers Supported Baud Rates Factory Defaults ASCII Pass-through Using USB to TTL RS232 Adaptor with Hardware Connection Download ASCII Pass-through Firmware Send Text Message Using a Serial Terminal Example Application References

4 1. Introduction The serial-to-plc adapter is a simple way to extend/replace an existing serial connection with a PLC without having to change any other software or hardware components. The adapter utilizes pass-through firmware that converts bytes from a serial port to PLC and from PLC to serial port. There are two pass-through variants: ASCII pass-through: Copies all ASCII characters, which are received on the UART, verbatim to the PLC line. Conversely, it forwards all ASCII characters received from the PLC line verbatim to the UART. The transmission to the power line in ASCII pass-through is triggered by the reception of a special ASCII character, normally "End of Line" or "Carriage Return" and can be changed on request. The configuration in ASCII pass-through mode can be changed using AT commands. TP pass-through: This variant of the pass-through firmware forwards all bytes from the UART (not necessarily ASCII) to the PLC line, and, conversely, forwards all bytes received from the PLC line verbatim to the UART. The transmission to the power line in TP pass-through mode is triggered by a time-out. Hence the name Timeoutbased Packetization (TP). The limitation of this mode is that there is no way to change the configuration. Note: At this time the ASCII pass-through and the TP pass-through firmware does not support the protocol used by the Semitech Graphical User Interface (GUI), which is available on most other firmware packages. Consequently, it cannot be used to communicate with the Serial-to-PLC adapter. Use serial terminal applications instead. The PLC device with ASCII pass-through or TP pass-through is ideal for industrial control applications to replace or extend RS232 or connections without having to modify other parts of the systems or any of the software protocols. At the end of this document, two - adapters with TP pass-through firmware are used as an example of the serial-to-plc adapter application. 2. Features Replacement of RS232 cable with DC or AC power line Replacement of multi-drop network with DC or AC power line Supports Modbus protocol Operational band: FCC (Cenelec-B/C version available) PLC PHY: OFDM (G3 FCC) or XXR (when additional performance is required) Effective PHY data rate up to 300 kbit/s (depending on band used) Serial port interface speed: up to 625 kbit/s Packet size: up to 350 characters Seamless PLC transmission with retries to improve performance Fully transparent mode (TP passthrough), plug and play coming out of the box without the need for any programming Serial and PLC configuration parameters are accessible via AT commands (ASCII pass-through) 4

5 3. Hardware Connection 3.1 Evaluate ASCII Pass-through Using the - The - can be used to evaluate ASCII pass-through by connecting an RS232 device to the host interface P1 header on the base board of the - as shown below. Figure 1. P1 Header on the - Base Board Table 1.P1 Header Pin List Pin# P1 P2 P3 P4 P5 P6 P7 Name 3V3 Mode1 Data Enable EX_UART_RX EX_UART_TX Reset GND 3.2 Replacing the Bus with Power Line via - with ASCII Pass-through This section shows the difference between the older bus network (Figure 2) and the newer bus network with RS232 devices (Figure 3) and devices (Figure 4). Master Bus Slave 1 Slave 2 Slave 3 Slave 4 Figure 2. Old Bus Network 5

6 Power Line RS232 Master RS232 Slave 1 RS232 Slave 2 RS232 Slave 3 RS232 Slave 4 Figure 3. New Power Line Bus Network with RS232 Devices Power Line RS232 to RS232 Master RS232 to RS232 to RS232 to RS232 to Slave 1 Slave 2 Slave 3 Slave 4 Figure 4. New Power Line Network with Devices 6

7 4. ASCII Pass-through Configurations This section describes the supported features of the ASCII pass-through configuration, including AT commands, AT registers, baud rates, and factory defaults. 4.1 Supported AT Commands Table 2 lists the supported AT commands. Command Note: When running ASCII pass-through firmware for the first time, it is important to run the AT&F command followed by the ATZ command. This is required to write ASCII-specific default settings to the Flash memory. 4.2 Supported AT Registers +++ Switch to command mode. ATO ATSr? Get Register r. ATSr= Set Register r. ATZ AT&F AT&MBM AT&MBS AT&MBC Table 3 lists the supported AT registers. Table 2. Supported AT Commands Description Switch to data (string tx) mode; this command ends with Satin letter "O", not with zero. Reboot device. Restore Factory Defaults (most defaults depend on PHY, see below). Make master. Note that register numbers 100 and above may be used for advanced physical-level PLC configuration. The alteration of these parameters from their default values is usually not required. However, in challenging circumstances, e.g. high interference or noise, this may be an option. The applicability and meaning of such settings depends on the PLC protocol. For more information, refer to the documents listed in Section 7, References, or contact Semitech Semiconductors should fine tuning of the physical parameters be required. Register Number Make slave (requires address as argument). Run given command. Table 3.Supported AT Registers 37 UART baud rate (37 is standard allocation for this purpose) PLC PHY configuration parameters. 100 Modulation code, 0 to Bits per baud. 102 Number of repetitions. 103 Number of frequencies. 104 Convolution code enable. 1: enable 0: disable 105 Tone map. A bit map containing a list of the sub-bands (groups of tones) that are either active (bit set to 1) or inactive (bit set to zero). A bit in the bit map represents a group of consecutive tones and the number of tones per group depends on the band plan. 106 Coherent mode. 1: enable 0: disable 7

8 Register Number 107 Delimiter. 0: SOF no response 1: SOF w/ response 2: ACK 3: NACK 108 On/Off mode. 1: enable 0: disable 109 Band select; XR-specific setting 110 SubCarriers; 4 decimal concatenated numbers, e.g. set of subcarriers " " is encoded as FCC enable (XXR protocol). 1: enable 0: disable 4.3 Supported Baud Rates Table 4 defines baud rates, which can be applied to UART using ATS command with register number 37 (conventional register for setting the baud rate). Example: 4.4 Factory Defaults ATS37 = 14: baud rate set to ATS37 = 16: baud rate set to Table 3. Supported AT Registers (continued) Mode Table 4.Supported Baud Rates Baud Rate 0 through and and Note: These higher baud rates might not be standard allocations Following are the default PLC parameters with ASCII pass-through or TP pass-through firmware, which are accessible for modification via AT commands in ASCII pass-through variants. 8

9 5. ASCII Pass-through Using USB to TTL RS232 Adaptor with - ASCII pass-through can also be tested using a USB to TTL RS232 adapter connected to the host interface connector P1 on the base board of the - as described in the top portion of Figure 5 below. 5.1 Hardware Connection Parameter/Mode Table 5. Factory Defaults Default UART baud rate (mode 15) XXR Modcod = 1 bitsprbaud = 1 repetition = 4 Subc2200 = G3 Modcod = 0 BitsperBaud = 1 Repetitions = 4 ToneMap = 0x03F Coherent = 1 Delimiter = 0 The connection to the UART port is available on the -M base board on the header P1, where pin 5 is external transmit, pin 4 is external receive, and pin 7 is ground as shown below. This UART port can be connected either directly to the TTL-level UART port on the host device (if available), or to a USB port via a USB-to-UART converter, also known as FTDI (Digikey Part No ND). The latter method of the connection is illustrated by Table 6 and Figure 5. Table 6. Connecting the FTDI Device to the - Base Board FTDI TTL-232R-RPi RXD (Yellow cable) TXD (Orange cable) GND (Black cable) - Base Board EX_UART_RX (Pin 4 of P1 Header) EX_UART_TX (Pin 5 of P1 Header) GND (Pin 7 of P1 Header) Please note that the mini-usb cable and the FTDI cable can't be used at the same time. 9

10 5.2 Download ASCII Pass-through Firmware Figure 5. FTDI TTL-232R-RPi Connection The img-passthru-g3-ascii-fcc bundle can be downloaded to the - FCC module using the Control GUI as described in the -EVK User Guide. If an FTDI cable is used for downloading, pin 1 (3V3) and pin 2 (Mode1) of header P1 must be connected via a jumper to pull the Mode1 pin high for downloading. This jumper is shown in Figure 6 below. After the download is complete, remove the jumper and power cycle the -. If a mini-usb cable is used for downloading, there is no need to manually control the Mode1 pin because it is controlled by the CP2110 on the - base board. 10

11 Figure 6. - FTDI TTL-232R-RPi Connection for Downloading 5.3 Send Text Message Using a Serial Terminal After downloading the ASCII pass-through firmware to two - systems, the ASCII messages can be sent between those two EVK systems over the power line via a serial terminal, e.g. Bray's Terminal ( This can be accomplished using the following procedure. 1. Connect each - to a PC using the FTDI TTL-232R-RPi cables as shown below. Power Line SM SM TT L-232R RPi Cable TT L-232R RPi Cable Figure 7. Connecting Each - to a PC 2. Start Terminal.exe 11

12 3. Once the terminal.exe program is invoked, connect the EVK to the terminal via the right COM port at a default baud rate of as shown in Figure 8. Figure 8. Set the Baud Rate to When running the ASCII PASSTHRU project for the first time on the board, which had other projects loaded before, it is important to run AT&F command followed by ATZ command. This is needed to write ASCII-specific default settings to flash. 5. Send ATO to switch to data mode. 6. Repeat steps 2 through 4 for the second Test any ASCII string from one terminal and it should be received and displayed on the 2nd terminal as shown in Figure 9. 12

13 Figure 9. Send Hello World from Terminal 1 Figure 10. Received from Terminal 2 with Retries 13

14 6. Example Application The following example illustrates an off-the-shelf sensor (inclinometer) managed remotely by introducing two PLC adapters between the sensor and the PC based GUI in a plug-and-play manner as shown in Figure 11. The scope image in Figure 12 shows the message propagation from the sensor to the PC and back. - - Figure 11. Inclinometer Example Configuration Figure 12. -to-plc Message Propagation 14

15 Figure 13. Transceiver Circuit to the - 7. References 1. Narrowband OFDM PLC specifications for G3-PLC networks, G3-PLC Alliance, April Specification for PoweRline Intelligent Metering Evolution, revision 1.4, Prime Alliance

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