User manual

FCC ID: JIL2188

Users Manual

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Preliminary Release

REVISION HISTORY

REV DESCRIPTION DATE
2.0 Initial Release 08/15/2019

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5.13 Telnet Session Activity Timer.........................................................................................................22
5.14 Log-in Session Activity Timer.........................................................................................................22
5.15 Enable Transmitter........................................................................................................................22
5.16 Enable Encryption..........................................................................................................................22
5.17 Enable Password Entry..................................................................................................................22
5.18 ID (Identification Number).............................................................................................................22
5.19 Password.......................................................................................................................................23
5.20 ES Encryption Phrase.....................................................................................................................23
5.21 Log Out..........................................................................................................................................23
5.22 Quit Telnet.....................................................................................................................................23
5.23 Forwarding Mode..........................................................................................................................23
5.24 Remote RTU0 MAC Address..........................................................................................................24
5.25 Remote RTU1 MAC Address..........................................................................................................24
5.26 Master RTU MAC Address Table....................................................................................................24
5.27 Host MAC Address Table...............................................................................................................24
5.28 High QOS (Quality Of Service) IP Address Table.............................................................................25
5.29 Loopback Remote MAC Address....................................................................................................25
5.30 Diagnostic Tests.............................................................................................................................25
5.31 Display Status Screen.....................................................................................................................26
5.32 Display RTU Table..........................................................................................................................26
5.33 Display Host Table.........................................................................................................................26
5.34 Display QIP Table...........................................................................................................................26
6.0 Theory of Operation............................................................................................................................27
6.1 RS-232 Communications................................................................................................................27
6.2 Ethernet Communications.............................................................................................................27
6.2.1 Packet Forwarding....................................................................................................................27
6.2.2 Telnet Radio Configuration and Diagnostics.............................................................................28
6.2.3 Graphics Heavy Communications.............................................................................................28
6.2.4 High QOS (Quality Of Service) IP Communications...................................................................28

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Introduction
Thank you for purchasing the Alligator Model 2188 UHF Radio Transceiver. We are here to
assist you personally should any questions arise in the installation or operation of this product.
Please feel free to call us. We look forward to your feedback and will strive to make our product
as compliant with your specific needs as possible.

1.1 General Description
The Alligator Communications Model 2188 is a microprocessor-controlled data radio
transceiver designed to operate in accordance with FCC rules, Part 90, FCC ID JIL2188. The 2188
data radio is frequency synthesized and programmable to individual transmitter and receiver
frequencies in the 150-174 MHz frequency band. The transceiver is a fixed channel, half-duplex
radio available with a channel bandwidth of 6.25, or 12.5 kHz. It interfaces with both Ethernet
and RS-232.

1.2 Applications
The 2188 data radio is designed for point-to-multipoint or point-to-point licensed operations in
the 150-174 MHz band. Some of the most common applications are:
 Electric Utility Substation SCADA
 Pipeline Flow Monitors
 Energy Distribution & Metering Applications
 Gas or Petroleum Production Well Head Control and Monitoring
 Water Distribution and Waste Water Collection Control and Monitoring
 Petroleum Production, Transmission, Storage and Distribution

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1.3 Technical Specifications

GENERAL
Frequency 150-174 MHz
Input Voltage 12-24 Vdc
Current Consumption (at 13.8 Vdc) <80 mA
Receive Mode 100 mA
Transmit Mode (3 Watts) < 1.2 A
Data Rate 9600 bps
Connectors
Antenna Type N female
Power 2-pin Captive, Rectangular
Data (RS-232) DB9F
FCC Certified FCC ID JIL2188
Environment
Temperature -30°C to +60°C
Humidity 95% at 40°C
Dimensions 6.75” x 1.5” x 5.75”
Weight 2 pounds

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TRANSMITTER
RF Power 3 W (max.)
Impedance 50 Ohms
Frequency Range 150 MHz-174* MHz
Frequency Step Size 1 Hz
Frequency Stability ±1 ppm
Modulation 4GFSK
Symbol Rate 4800 Hz**
Data Rate 9600 bps
Maximum Frequency Deviation 2400 Hz**
Attack Time <1 msec
Release Time <0.5 msec
Bandwidth 6.25 or 12.5 kHz**

RECEIVER
Input Sensitivity -117 dBm at 10-6 BER
Impedance 50 Ohms
Frequency Range 150 to 174* MHz
Frequency Step Size 1 Hz
Frequency Stability ±1 ppm
Selectivity 100 dB
Desensitization -60 dB
Intermodulation -75 dB (EIA)
Spurious Image Rejection -80 dB
Bandwidth 6.25 or 12.5 kHz**
*Other frequency bands available on special
order
**Other bandwidths available on special order
by changing symbol rate and frequency
deviation

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1.4 Warranty
Alligator Communications, Inc., warrants each of the instruments of its manufacture to meet
the specifications when delivered to the BUYER; and to be free from defects in material and
workmanship. Alligator Communications will repair or replace, at its expense, for a period of
one year from the date of delivery of equipment, any parts that are defective from faulty
material or poor workmanship. This Warranty does not cover equipment which has been
misused and/or altered by the user.
Instruments found to be defective during the warranty period shall be returned to the factory
with transportation charges prepaid by the BUYER. It is expressly agreed that replacement and
repair shall be the sole remedy of the SELLER with respect to any defective equipment and
parts hereof and shall be in lieu of any other remedy available by applicable law. All returns to
the factory must be authorized by the SELLER, prior to such returns. Upon examination by the
factory, if any instrument is found to be defective, the unit will be repaired and returned to the
BUYER, with transportation charges prepaid by the SELLER. This warranty does not apply to
equipment which, in the opinion of the SELLER, has been altered or misused.
NO OTHER WARRANTY IS EXPRESSED OR IMPLIED. ALLIGATOR COMMUNICATIONS IS NOT
LIABLE FOR CONSEQUENTIAL DAMAGES.

1.5 Claims for damage in shipment
The instrument should be inspected and tested as soon as it is received. If the instrument is
damaged in any way, or fails to operate properly, a claim should immediately be filed with the
freight carrier, or, if insured separately, with the insurance company.
WE PLEDGE OUR IMMEDIATE AND FULLEST COOPERATION TO ALL USERS OF OUR ELECTRONIC
EQUIPMENT.
PLEASE ADVISE US IF WE CAN ASSIST IN ANY MANNER:

Alligator Communications, Inc.
1400 Coleman Avenue
Santa Clara, CA 95050
Phone: (408) 327-0800
FAX: (408) 327-0808
E-mail: info@alligatorcom.com
Website: www.alligatorcom.com

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2.0 Radio Configuration and Operational Check

2.1 General Discussion
Prior to customer installation and electrical connection of the customer’s terminal equipment
to the 2188 radio, it is recommended that the installing technician conduct a brief operational
checkout of the 2188 radio and confirm that all operating parameters are set as desired.
This initial checkout and possible reprogramming/customization is generally performed on the
maintenance shop test bench before the radio is installed and commissioned in a link
application.
The following parts of this section provide guidance in this checkout process and illustrate
alternate configurations and paths to perform the initial checkout.

2.2 Operational Bench Test
To ensure that the 2188 radio is functional prior to installation at the desired site, it is highly
recommended that the following tests be performed in sequence: (Please refer to 2.2.3 Initial
Checkout.)

2.2.1 Antenna Connector
The 2188 radio antenna port (RF Connector) is a coaxial, female, Type N connector. This
connector mates with a male cable connector, Type N such as Amphenol 3900, Andrew L44N,
or MIL Type UG-21. Under most circumstances, bench tests are conducted with a service
monitor (manufactured by IFR Inc., Marconi Instruments Ltd., Hewlett-Packard, Motorola, etc.).

CAUTION
The transmitter should not be keyed on or placed in the transmit
mode without a load connected to the antenna port to prevent
damage to the 2188 radio Power Amplifier due to long periods
(more than 10 minutes) of severely high SWR. An antenna, service
monitor, or dummy load should be attached to the antenna port.
The 2188 radio power output is approximately 3.0 Watts
maximum, so if a service monitor is connected to the antenna port,
ensure that the service monitor’s input port can handle at least a
10 watt input to avoid damaging the service monitor.

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3.0 Field Configuration and Verification
Prior to field installation of the 2188, it is crucial that that bench configuration and testing be
done using cables and RF attenuators to duplicate the deployed system or subsystem. This adds
confidence that the configuration has been done properly and stream-lines field installation.
Each remote configured 2188 must be tested with a master configured 2188 to verify proper
operation. This places deployed radios in final configuration so no additional programming is
necessary when final field installation is performed. This is highly recommended for a smooth
system deployment.

3.1 Field Configuration Bench Test
1. Update the 2188 IP address to the desired fielded IP address. Each 2188 must be
assigned to a unique IP address in the subnet of the access point router. For example,
ip=10.0.0.5<CR>. Once this instruction is entered, the Telnet connection is lost and must
be re-established on the new IP address.
2. Re-establish Telnet communications on the new IP address. Typically use a second lap-
top with its IP address configured to the desired IP subnet range and with a copy of
puTTY that can start a Telnet session with the 2188 on the newly assigned IP address.
3. Assign the access point router gateway IP address. For example, gw=10.0.0.1<CR>.
4. Assign the subnet mask. For example, sm=255.255.255.0 .
5. If desired, assign a different Telnet port from the default port 23. For example,
tnp=50000<CR>. If you change the Telnet port, you lose the session and must reconnect
on the newly assigned port number with puTTY.
6. Assign a group code if desired to identify a unique group of radios. This blocks accidental
communications with other 2188 radios. For example, gc=3<CR>.
7. Decide if the 2188 is a master or remote. There is only one master 2188 radio in a point-
to-point or point-to-multipoint radio network. For a master, configure with the
command om=1<CR>. For a remote, configure with the command om=0<CR>. The
primary difference between a master and remote is that a master passes host polls and
other unsolicited messages. The remote radio passes responses from the polled RTU.
Occasionally the RTU generates unsolicited transmissions to the remote radio. This
causes no disturbance to the polling process. The remote radio buffers the packet(s)
until a clear time to send back to the host. Note that both the master radio and remote
radios are transparent to the protocols encapsulated in the Ethernet packets or RS-232
serial data.
8. If using RS-232, select the terminal data rate. The data rate can be selected from 1200,
2400, 4800, 9600, or 19200 bps. For example, dr=9600<CR> selects 9600 bps. Note that
in RS-232 systems, the Ethernet connector is still used for Telnet control of the 2188.
The 2188 can handle RS-232 and Ethernet concurrently.
9. The 2188 has various forwarding modes to limit Ethernet access to the radio network at
both the master and remotes ends of the radio link. This aids in preventing flooding the
radio network with unwanted packets. The 2188 shipping default is fm=3<CR>. This

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14. The 2188 can operate using the AES256 encryption standard with the following
commands:
ee=0<CR> no encryption
ee=1<CR> AES256 encryption

No encryption results in the least number of extra characters appended to a message.
This minimizes transmission latency. Encryption will pad extra randomized characters to
create standardized message segment lengths of 128 bits. The pad characters are
removed at the receiver.

The AES256 standard uses a 256-bit key. The key is generated from a user generated
phrase. This phrase can be up to 32 case sensitive characters. It is entered with the
command: aesp=### . . . ###<CR>. The phrase is converted into a 256 bit key using the
SHA256 secure hashing algorithm. This key is used by the AES256 encryption and
decryption algorithms.
15. Should it be necessary, the transmitter can be disabled with the command: et=0<CR>.
To re-enable the transmitter: et=1<CR>.

4.0 Front Panel Indicators
The six front panel LEDS are defined in Table 1:

LED Description
PWR On when 12 Vdc power is applied.
RXD1 On when receive data is active.
RXD2 On when diagnostic receive data is active.
DCD On when receive data preamble is detected.
TXD1 On when transmit data is active.
TXD2 On when diagnostic transmit data is active.
Table 1 LED Definition

The LEDs show the status of both Ethernet and RS-232 serial data. Diagnostic data occurs during
Telnet sessions.

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5.4 Transmit Power
The 2188 transmitter output power has three power settings:
1 Low (1 W)
2 Medium (2 W)
3 High (3W)

tp=x<CR>
Examples: tp=1<CR> tp=2<CR> tp=3<CR>

5.5 Operational Mode
The 2188 has two operational modes:
0 Remote
1 Master

Systems can be configured for single or dual frequency. No advantage in latency is gained by
using two channel frequencies.
Systems use 1 master (om=1) and up to 512 remotes (om=0). It requires that the master have
line of sight to all remote radios.
om=x<CR>
Examples: om=0<CR> om=1<CR>

5.6 Group Code
To prevent confusion of two or more separate 2188 systems, there are 16 unique group codes
to distinguish 2188 groups, ranging from 0 to 15. The default group code is 0.
gc=##<CR>
Examples: gc=0<CR> gc=1<CR> gc=15<CR>

5.7 IP Address
Each 2188 radio must be assigned a unique IP address within its LAN subnet group. This permits
both local and remote access of radio configuration and status information. The default IP
address is 192.168.1.128. It must be changed prior to field deployment. The IP address assigned
to the radio is for diagnostic purposes to control and monitor the 2188 locally or remotely.
ip=###.###.###.###<CR>
Examples: ip=10.0.0.100<CR> ip=172.16.10.100 ip=192.168.1.10<CR>
If the IP address is changed to a new subnet, make certain that the computer is also changed to
the new subnet.5.8 Telnet Port
The 2188 Telnet port can be reassigned from the default of 23 to any port up to 65535. This
adds additional security to the system.

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tnp=#####<CR>
Examples: tnp=23<CR> tnp=1000<CR> tnp=65535<CR>

5.9 Gateway Address
The 2188 must be given the gateway router IP address within its LAN subnet group. Normally it
is the first IP subnet address ending in 1.
gw=###.###.###.###<CR>
Examples: gw=10.0.0.1<CR> gw=172.16.10.1 gw=192.168.1.1<CR>

5.10 Subnet Mask
The 2188 must be given a subnet mask. The default is 255.255.0.0
sm=###.###.###.###<CR>
Examples: sm=255.255.0.0<CR> sm=255.255.255.0

5.11 RS-232 Data Rate
The 2188 has a DB9 connector to permit using an RS-232 interface. The asynchronous data
format is one start bit, eight data bits, and one stop bit with no parity. The data rate can be set
to one of five possible rates: 1200 bps, 2400 bps, 4800 bps, 9600 bps (default), and 19200 bps.
dr=####<CR>
Examples: dr=1200<CR> dr=2400<CR> dr=4800<CR> dr=9600<CR> dr=19200<CR>

5.12 Anti-streaming Timer
The transmitter key on time is timed to prevent disrupting the channel. The maximum on time
is the anti-streaming time defined in seconds. The default is 120 seconds. This is most often
invoked when performing testing with a CW carrier that is activated remotely.
ast=####<CR>
Examples: ast=120<CR> ast=9999<CR>

5.13 Telnet Session Activity Timer
The 2188 times activity when engaged in Telnet communications. If there is inactivity for more
than the specified time duration in seconds, the Telnet session is automatically terminated. The
default Telnet session activity timer default is 120 seconds.
tnt=####<CR>
Examples: tnt=300<CR> tnt=9999<CR>

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5.14 Log-in Session Activity Timer
The 2188 times activity when using password access (pw=1). If there is inactivity for more than
the specified time duration in seconds, the log-in session is automatically terminated. The
default log-in session activity timer default is 120 seconds.
lgt=####<CR>
Examples: lgt=300<CR> lgt=9999<CR>

5.15 Enable Transmitter
The 2188 transmitter can be enabled for normal operation or forced to be disabled by this
command.
et=#<CR> 0 = disable transmitter 1 = enable normal transmitter operation
Examples: et=0<CR> et=1<CR>

5.16 Enable Encryption
The 2188 can encrypt data for additional data security. This command selects encryption.
ee=#<CR> 0 = disable encryption 1 = enable AES256 encryption
Examples: ee=0<CR> ee=1<CR>

5.17 Enable Password Entry
The 2188 can restrict access by forcing an id and password before access is granted.
ep=#<CR> 0 = disable password entry 1 = enable password entry
Examples: ep=0<CR> ep=1<CR>

5.18 ID (Identification Number)
When password entry is enabled (ep=1), this ID must match to gain access to the 2188. The ID is
case sensitive and can be any set of up to 16 characters, including letters, numbers, and
punctuation marks. The default id is “admin”.
id=###. . .###<CR>
Examples: id=<CR> id=admin<CR>

5.19 Password
When password entry is enabled (ep=1), this password must match to gain access to the 2188.
The password is case sensitive and can be any set of up to 16 characters, including letters,
numbers, and punctuation marks. The default password is password.
pw=###. . .###<CR>
Examples: pw=<CR> id=password<CR>

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5.20 ES Encryption Phrase
When encryption is enabled (ee=1), a case sensitive phrase of up to 32 characters including
letters, numbers, and punctuation marks is hashed to a 256-bit AES256 encryption key using the
SHA256 secure hashing algorithm. This key is used encrypt and decrypt 128- bit message
fragments used in the AES256 encryption standard.
aesp=###. . .###<CR>
Examples: aesp=<CR> aesp=mydoghasfleas<CR>

5.21 Log Out
When password entry is enabled (ep=1) after a session is complete, the user logs out using the
command:
lo<CR> (lower case L lower case O)
If the lo<CR> is not entered, then the session timer will automatically perform the log out after
timing out.

5.22 Quit Telnet
To quit a Telnet session:
q<CR>

5.23 Forwarding Mode
The 2188 forwards all RS-232 transmissions; however, Ethernet packets are forwarded more
selectively to avoid RF network flooding. There are four forwarding modes:
1 RTU and Host (qualified RTU and Host source/destination MAC address)
2 Host (qualified host source/destination MAC address)
3 RTU (qualified RTU source/destination MAC address)
4 All (No filtering, all packets forwarded)
fm=#<CR>
The factory default is fm=3, but it is highly recommended that it be changed to fm=1 (host
forwarding) to prevent flooding. Host filtering is easily done by entering the host MAC address
in the host and remote 2188 radios. At the master only host sources are forwarded. At the
remote only host destinations are forwarded. Up to 16 host MAC addresses can be placed in
the host MAC address table.
RTU MAC address filtering offers additional traffic flooding protection. The master radio can
store up to 512 remote RTU MAC addresses. The remote radios can store up to two RTU MAC
addresses associated with the RTUs connected to that remote radio.
Examples: fm=0<CR> fm=1<CR> fm=2<CR> fm=3<CR>

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5.24 Remote RTU0 MAC Address
This is the RTU MAC hexadecimal address of the first RTU connected to a remote 2188. It is
stored at the remote 2188 and is used when the remote radio is in forwarding mode 0 or 2.
rtu0=##-##-##-##-##-##<CR>
Example: rtu0=01-23-45-ab-cd-ef<CR>

5.25 Remote RTU1 MAC Address
This is the RTU1 MAC hexadecimal address of the second RTU connected to a remote 2188. It is
stored at the remote 2188 and is used when the remote radio is in forwarding mode 0 or 2.
rtu1=##-##-##-##-##-##<CR>
Example: 01-23-de-ad-be-ef<CR>

5.26 Master RTU MAC Address Table
This is the command format for entering RTU hexadecimal addresses in the master radio RTU
table. It is used when the master is in forwarding mode 0 or 2. Up to 512 RTU MAC addresses
may be saved in the master RTU MAC address table. Both RTU number (000 to 1ff) and
associated MAC address are in hexadecimal. The table is initially cleared to all zeros. Normally
the table is filled, starting at 000 and progressing to a maximum number of 1ff. The entire table
is scanned for each forwarding operation by the master radio when fm=0 or fm=2.
rtu[###]=##-##-##-##-##-##<CR>
Example: rtu[000]=01-23-45-ab-cd-ef<CR> rtu[1ff]=01-23-de-ad-be-ef<CR>

5.27 Host MAC Address Table
This is the command format for entering host hexadecimal addresses in the 2188 host table. It
is used when either the master or remote radio is in forwarding mode 0 or 1. Up to 16 host
MAC addresses may be saved in the host address table. Both host number (0 to f) and
associated MAC address are in hexadecimal. The table is initially cleared to all zeros. Normally
the table is filled, starting at 0 and progressing to a maximum number of f. The entire table is
scanned for each forwarding operation by the master or remote radio when fm=0 or fm=1.
host[#]=##-##-##-##-##-##<CR>
Example: host[0]=01-23-45-ab-cd-ef<CR> host[f]=01-23-de-ad-be-ef<CR>

5.28 High QOS (Quality Of Service) IP Address Table
This is the command format for entering high QOS IP addresses in the 2188 QIP table. Most
commonly the IP address of polling host computers is entered into both the master radio QIP
table and all remote QIP tables. This gives priority for high QOS device sources at the master
radio and high QOS destinations at the remote radios.

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Up to 16 IP addresses may be saved in the QIP table. Host number (0 to f) is in hex and
associated IP addresses are in standard dot notation. The table is initially cleared to all zeros.
Normally the table is filled, starting at 0 and progressing to a maximum number of f.
Note that RS-232 always has high priority since it is most commonly used for polled systems.
host[#]=###.###.###.###<CR>
Example: host[0]=192.168.1.2<CR> host[1]=192.168.1.3<CR> host[f]=10.0.0.10<CR>

5.29 Loopback Remote MAC Address
This is the remote radio hexadecimal MAC address placed in the master radio when performing
the loopback diagnostic test (dt=5). Note that Alligator 2188 radios are currently assigned to
MAC addresses starting with 70-b3-d5-9c-e.
lb=##-##-##-##-##-##<CR>
Example: lb=70-b3-d5-9c-e0-00

5.30 Diagnostic Tests
There are several different diagnostic tests that can be performed using the dt command:
1 TX CW
2 RX CW
3 TX 1 Way
4 RX 1 Way
5 TX 2 Way
6 Display TX Buffer
7 Display RX Buffer
8 Display TX and RX Buffers
9 Display Sub-packet Types

dt=#<CR> Note that <ESC> terminates the test, returning to dt=0.
Example: dt=1<CR> dt=5<CR>
The default at power-up is 0 (none).

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5.31 Display Status Screen
The status screen is displayed by two methods:
<ESC> a single press of the escape key
<CR><CR> a double press of the carriage return (ENTER key)

5.32 Display RTU Table
The entire 512-entry RTU table is displayed:
rtutable<CR>

5.33 Display Host Table
The entire 16-entry host table is displayed:
hosttable<CR>

5.34 Display QIP Table
The entire 16-entry QIP table is displayed:
qiptable<CR>

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6.0 Theory of Operation
The 2188 concurrently operates transparently using two communication interfaces: Ethernet
and RS-232 (Fig. 1). The 2188 encapsulates any protocol in a proprietary Alligator format to
encrypt and forward multiple packet fragments across a UHF radio link and reassemble them
seamlessly. It is most easily understood as a wire transmission with added latency due to time
taken for transmission over a 12.5 kHz channel at 9600 bps along with delays due to packet
screening, assembly and encryption.

6.1 RS-232 Communications
The RS-232 communications interface forwards all incoming serial data with no screening. It
operates at one of five programmable data rates: 1200, 2400, 4800, 9600, and 19200 bps.
There is no RTS or CTS data flow control required because data is forwarded based on TXD line
activity. This permits a simple three wire interface consisting of TXD, RXD, and GND.

6.2 Ethernet Communications
All Ethernet packets (UDP, TCP/IP, Ping, ARP, . . .) are recognized and can be transparently
forwarded over the RF network.
6.2.1 Packet Forwarding
The Ethernet communications interface forwards incoming IP packets, provided that they pass
a user-programmable forwarding screening test. Packet forward screening is done to minimize
data traffic not intended for the radio network that could otherwise flood the system. The 2188
has four programmable forwarding modes:
1. No Screening
2. Host Screening
3. RTU Screening
4. RTU and Host Screening
The simplest forwarding mode does not screen any packets. This is referred to as the IP
promiscuous mode and is only used in small systems where flooding by unwanted packets is
improbable. It is not recommended in systems with either the master or remote ends tied to
LANs due to the flooding potential. The 2188 defaults in this mode for testing but is not
recommended for field deployment.
The host screening mode is highly recommended for packet forwarding on the master radio. At
the master radio, a host table with up to 16 entries is created by the user with a list of host
MAC addresses. Only packets originating by authorized hosts on the MAC table are forwarded.
The remote radio can also be configured for host filtering. This causes the remote radio to
forward only packets originating from the RTU back over the RF link that are destined for an
authorized host MAC address. This greatly reduces the probability of system flooding.
The RTU screening mode is used so that only packets destined for authorized RTU MAC
addresses are forwarded. At the master radio, an RTU table with up to 512 entries is created by

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the user with a list of RTU MAC addresses. Only packets destined for authorized RTUs on the
MAC table are forwarded. The remote radio can also be configured for RTU filtering. This causes
the remote radio to forward only packets back over the RF link when they are sourced by an
authorized source RTU MAC address. This also greatly reduces the probability of system
flooding.
The combined RTU and Host screening mode provides the greatest amount of filtering. Only
authorized traffic has access to the radio address with both source and destination MAC
address complying with the system definition. This makes system flooding nearly impossible to
occur.
6.2.2 Telnet Radio Configuration and Diagnostics
The primary mission of the 2188 is to provide robust RF linkage with total protocol
transparency; however, a Telnet server for local and remote radio configuration is provided in
each 2188. Thus, each 2188 is factory-assigned a unique Alligator MAC address for IP access
using the Telnet protocol. The user is able to program the IP address, gateway address, subnet
mask, and Telnet port address. This gives the radio visibility to the host and/or a separate client
host for radio configuration and diagnostics. Users of RS-232 interfaces also use the Ethernet
interface with a Telnet client program. The Telnet communications over the RF link shares the
bandwidth of the system transparently.
6.2.3 Graphics Heavy Communications
The use of communications carrying a large amount of graphics data is discouraged. Please be
aware that at 9600 bps, the transmission rate is only about 1K bytes per second. Sending large
graphics files can take tens of seconds. This can be done concurrently with the normal polling
traffic along with Telnet diagnostic traffic, but at the cost of system time latency. Nothing
prohibits doing large file transfers, but be aware of the time required to push the data through
a 9600 bps link. IP addresses associated with this type of traffic should not be placed in the QIP
table (see 6.2.4).
6.2.4 High QOS (Quality Of Service) IP Communications
IP packets can be assigned high QOS status. This is performed by storing the IP address in a QIP
table. These tables reside in both the master and remote radios. Up to 16 IP addresses can be
saved in the QIP table. This table normally contains the IP addresses of hosts that are polling
remote RTUs and require low timer latency. RS-232 packets are assigned high QOS by default.

Alligator Communications Model 2188 Technical Manual REV3.0 Copyright © 2019 Page 27

FCC Statement
1. This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:
(1) This device may not cause harmful interference.
(2) This device must accept any interference received, including interference that may cause undesired operation.
2. Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority
to operate the equipment.
NOTE:
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the
FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential
installation.
This equipment generates uses and can radiate radio frequency energy and, if not installed and used in accordance with the
instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will
not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which
can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or
more of the following measures:
Reorient or relocate the receiving antenna.
Increase the separation between the equipment and receiver.
Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
Consult the dealer or an experienced radio/TV technician for help.
The antenna(s) used for this transmitter must be fixed-mounted on outdoor permanent structures.

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Document Created: 2019-09-24 15:58:26
Document Modified: 2019-09-24 15:58:26

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