1.126 Comstream-CM701-MC

This page describes the device driver and the device window for the Comstream CM701 Satellite Modem for configurations using a single 5MBit / 512kBit Modem card and - optionally - a framer/buffer card and a Reed-Solomon card. This driver does not work with the old type of the lo-speed modem card.

Although this driver is capable to handle a CM701 equipped with a single modem card in a SCPC configuration, it is optimized for applications which make use of the framer option board or the Reed-Solomon codec. The driver does not allow to have an additional modem card, modulator or demodulator installed beside the primary card as it does not use slot addressing with the commands sent to the modem.

The driver automatically recognizes the presence of a framer/buffer or a Reed-Solomon card and enables the parameter settings belonging to these option cards at the user interface. For your convenience, the modem driver uses the "Primary Data Rate" macros of the CM701. These macros automatically compute and set the input/output data rates for the framer and the Reed-Solomon option modules when you enter a data rate value.

Comstream CM701 device driver overview

The Comstream CM701 satellite modem may be operated in many different configurations. The modular architecture of this device permits to compose a modem from modulator, demodulator and option cards as well as to run up to three modem cards in one device frame.

With the sat-nms software, there is a family of device drivers which cover the most usual configurations for the CM701. Basically there are two groups of drivers: The first one covers applications which make use of the option cards like the framer/buffer card for IDR or the Reed-Solomon codec. This group is limited to single channel (one modulator, one demodulator) usage.

The other group covers multi-channel applications which run up to three modem, modulator oder demodulator cards in one device frame. These drivers are limited to plain SCPC applications, they do not support any option cards. You may put two modem cards and a modulator card in a CM701, these cards will be treated individual devices with the sat-nms software. Below there is a list of the available drivers for the CM701:

Modem cards, modulator cards and demodulator cards may be mixed in one CM701 frame if they are operated with a driver marked as MULTI-CH.

Device window pages

The following table shows which device window pages are available with this individual device type. Tool-bar functions not mentioned here are described at the general description of device windows .

• --- The IF parameters (frequency, level, etc.) and some global modem settings.
• --- The modulator settings, transmit clocking.
• --- The demodulator settings, receive clocking, doppler buffer.
• --- The TX interface settings.
• --- The Reed-Solomon settings.
• --- The framer option board settings.
• --- The RX interface settings.
• --- The receive quality.
• --- The faults page.
• --- The device info page.
• --- The maintenance page. The configuration parameters described below are set at this page.

Configuration parameters

At the maintenance page of the device window there are a couple of configuration parameters which must be set to make the software talk to the CM701.

• parameter --- description
• address --- The modem's RS485 packet address. Valid addresses are 1..31, 31 is the factory default. If you have multiple devices connected to one RS485 bus, each device must have it's unique address. If you want to access a CM701 through a CX801/CX101 protection switch, you have to prepend the address of the CX801/CX101 separated by a comma: "1,15" addresses the modem "15" through the protection switch "1".
• type --- Adjust this parameter to the data rate range of the modem card (512kBit / 5MBit). *faultMask --- The modem's fault mask (both, the STO and the FO mask). Common values are:
  • 4294967295 --- All faults enabled.
  • 1440583691 --- RX faults disabled (TX-ONLY mode)
  • 2863594484 --- TX faults disabled (RX-ONLY mode)

See the Comstream manual for mode details.

• faultLogMask --- The modem's fault log mask (FLO), coded in the same way as "faultMask".
• txAutoOn --- The carrier state when the modem gets powered on.
• txFaultOff --- Defines if the modems switches off the carrier on some faults conditions.
• vsatMode --- Turns the VSAT mode on/off
• demodLength --- The "DL" parameter. See the Comstream manual for details.
• Serial --- Remember to set the line parameters for the serial interface connected to the CM601. While the CM601's factory preset setting is 1200,O,7,1 , the recommended line setting for the use with the sat-nms software is 9600,O,7,1 .

Communication protocol / Interface type

The recommended communication protocol for the CM701 is the Comstream-Packet-Protocol (The driver works with the Comstream-ASCII-Protocol , too, but there are several issues when using the ASCII protocol (unsolicited "ST/FL" reports, multi-line terminal commands). You are free to use either a RS232 or a RS485 interface to access the modem.

Commonly Asked Questions

The CM701 does not seamlessly fit into the M&C software concept at some points. Commonly asked questions arising from these issues are answered below.

• The data rate field at the user interface contains no value. What happened? --- The primary data rate macros used to program the modem do not work in both directions. If a data rate is set, the CM701 remembers this value and reports it to the software as the actual setting. This setting is cleared if any intermediate data rate value is changed (e.g. the symbol rate). After power on, the CM701 does not report a valid data rate.
• One of the IF frequency fields at the user interface contains no value. Is this a similar issue? --- The CM701 uses a flexible format for IF frequency values. It remembers the number of digits the last command contained and replies to all following requests with this number of digits. This may lead to a wrong reading if the modem is operated with the software the fist time. Once the frequency has been set by the software one time, the CM701 reports the correct frequency value and the software display this.
• What do the "set to xxx but reported yyy" messages in the event log mean? --- The range of some parameters of the CM701 depend on other parameter settings. For instance, the Reed-Solomon scrambling type only can be selected, if the Reed-Solomon codec is present and enabled. If not, the CM701 reverts to the old setting an one of these messages appears in the event log. Another parameter commonly causing such messages is the doppler buffer size. The value always must be a power of two, the CM701 automatically uses the next possible value above if you enter some other numbers.

Variables defined by this device driver