Specifications

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Using the common and specified 0-5VDC bi-directional electrical methods, the maximum practical cable length

is 1200 meters with no minimal length. With proper cable twist and shielding, maximum data rates are 10

Mbit/s at 12 m or 100 kbit/s at 1200 meters. Even though EIA-422 and EIA-485 share the same electrical

interface hardware, the EIA-422 communications standard cannot implement a truly multi-point

communications network, however one driver can be connected to up to ten receivers when the load is

properly balanced. This is due to the fact that the communications protocol for EIA-485 contains device

addresses where the protocol for EIA-422 does not.

A common use of EIA-422 is for RS-232 extenders. Pason, in effect, uses the EIA-422 interface, as a RS-232

serial device extender for all devices wishing to utilize the WITS information system.

According to Pason EDR Version 3.0+, when Pason RS-422 WITS interface is connected to distal equipment

the proximal Pason equipment is generally set to AUTO. In this mode, the distal equipment is required to set

up the communications baud rate, and serial data parameters to the Pason WITS system using the required

WITS null packet.

This is done by the distal equipment (Bloodhound) sending the WITS packet 0111 as a null:

NOTE: The WITS packet 0111 sent as a null is known as a null packet.

Example:

&&[CR]

0111-9999[CR]

!![CR]

Where [CR] is a carriage return ASCII character

This packet is sent repeatedly to the proximal Pason system. When this occurs, and the distal equipment is

connected to an EDR port that has not been damaged from a prior lightning event, the cabling is intact and

connected at both ends, and there is no inducted noise due to close proximity high voltage power lines, the

proximal port is supposed to change from AUTO to the baud rate, bit count, parity, and stop bits at which the

distal equipment is transmitting.

At that time the distal equipment can maintain the connection to the proximal Pason system by changing from

a null packet to general WITS packet information such as gas units or lag information. If the distal equipment

does not want to send the proximal Pason system WITS information, the distal system can maintain the

connection and reception of WITS information by continuing to send the null packet.

Currently, the Bloodhound system expects to communicate to the Pason EDR system at 9600 baud, 8 data

bits, 1 stop bit with no parity. This can be changed remotely by IBall Instruments technicians.

D. Bloodhound Minimum Data Packet

The Bloodhound has a second type of data packet. This packet is used to make the storage of data into

smaller files so that the files will take less time to transmit. The minimum packet is always the packet stored

on the SD card and the USB memory stick.

Bloodhound minimum packet example.

@,080420,111341,187955,2001.6,2001.6,8.09,20.89,0.60,11.347,1809,1.240,0,123.6,46

.3,23,12,1004,18,10,

1 The @ character String Start of packet character

2 Year/Month/Date String Date

3 Hour:Minute:Seconds String Time

4 Packet Number ULong 0 – 4 Billion

5 Drill Depth Float 0.0 – 60,000.00

6 Bit Depth Float 0.0 – 60,000.00

7 Gas Units Float 0.0 – 10,000.00