Law Enforcement Software
Law Enforcement Software
Regardless of the communications backbone used (Serial Radio, TCP or UDP) there are some communications setting that are applicable to all environments. These more generic settings control certain aspects of the communication and can be adjusted as necessary to achieve more optimal performance. These setting exist (or should be added) to the [MDC] section of the INI file and will be required by both MDC Workstations and the MDC Controller but may have different values on different machines.
[MDC]
ADDRESS=1
MAXPACKETSIZE=
MAXRETRYCOUNT=
MAXRETRYDELAY=
The ADDRESS setting should be unique for each MDC Workstation. The MDC address of zero ( ADDRESS=0 ) is reserved for the MDC Controller and there should be only one MDC controller in your MDC system. All MDC Workstations should have a unique address between 1 and 9999 that identifies that specific mobile device. If possible it may be easiest to simply use the vehicle ID number as the MDC Address number. If two or more cars have the same MDC address then they will constantly interfere with each other creating unreliable communications results.
The MAXPACKETSIZE entry of the INI file is used to determine the maximum size of a data packet sent by the MDC software. This setting can be used to optimize communications throughput. Since all data transmissions are broken into packets a larger packet size means that each message consists of fewer packets. Fewer packets mean fewer radio transmissions and greater speed of message delivery. However, larger packets are more susceptible to interference, corruption or damage during transmission, thus packet sizes that are too large may require more retry transmissions which could slow message delivery or cause message delivery to fail. For IP based communications the default setting of 512 may be too low. Generally a setting of 1024 (1K) data packets is probably a good choice. However, this setting should not exceed the maximum packet size of network infrastructure you are using. For Serial RF based communications the default value of 512 is acceptable. When using Serial RF modems the same basic rules about packet sizes and optimizing performance apply however this value should never exceed that maximum capacity of input data buffer on the RF Modem. The MAXPACKETSIZE entry should generally be the same for all MDC computers (Workstations and Controller).
Each time a data packet is transmitted the MDC sends an acknowledgment of packet receipt back to the sender. If a packet is sent and no acknowledgment is received, the sending MDC will resend the data packet. This is referred to as a RETRY. Retries are important in a mobile environment since the car may be temporarily going through a tunnel, behind a building or otherwise be in a location where radio communications are temporarily interrupted. The MAXRETRYCOUNT setting determines how many times the MDC will attempt to deliver a data packet before declaring the recipient unreachable and giving up. The default is 5. If the communication backbone is based on a private IP radio system, that system MAY employ its own strategy for retries and failed delivery’s. In circumstances where a private IP based system buffers data and handles message retries external from the MDC software, this setting should not be increased, and the MAXRETRYDELAY (discussed below) may need to be increased to give that external process time to deliver the message before the MDC tries to send the data packet again. However in circumstances where no retry mechanism external to the MDC exists, increasing the MAXRETRYCOUNT value can increase the likelihood of a successful message delivery.
The MAXRETRYDELAY setting determines how many seconds the MDC will wait without receiving an acknowledgment before attempting a retry sending a data packet.