Specifications

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NOTE: On sites with a Pason EDR system, just because the Pason cable can fit into a connector found on the

site does not mean that the connection will work. Pason advises to always connect the Bloodhound to the

Toolpush Connection Panel on the outside of the Rig Manager’s trailer, or, if that is not present, then to the

Toolpush Computer itself via one of the cables attached to it. (In the event that Pason does not have

somewhere to mount the Toolpush Connection Panel, they leave cables extending outside of the Rig

Manager’s trailer with the RS422 connectors accessible. In that case, they are simply cable ends, so are not

labelled.) Always connecting to the Toolpush Connection Panel or the Toolpush Computer will ensure that the

proper connection is made and the TPC will not require any configuration change to receive WITS.

Communication Hardware

The Bloodhound system has integrated an improved and electrically isolated RS-422 interface that directly

connects to the Pason EDR system utilizing the common Pason 10 pin interface cabling system.

Improvements include the addition of input current limiting resistors, over/under voltage protection diodes,

isolated grounding, and a 500 volt electrical isolation barrier between the external interface and the internal

electronics.

Communication Specifics

American national standard ANSI/TIA/EIA-422-B (formerly RS-422) and its international equivalent ITU-T

Recommendation V.11 (also known as X.27), are technical standards that specify the "electrical characteristics

of the balanced voltage digital interface circuit". It provides for data transmission, using balanced or differential

signaling, with unidirectional/non-reversible, generally resistively balanced and terminated transmission lines,

point to point, or multi-drop communication systems. In contrast to EIA-485 (which is multi-point instead of

multi-drop), EIA-422/V.11 does not allow multiple drivers but only multiple receivers. Pason only uses the

interface as a point to point wiring system between a central communications hub and a distal communications

device.

The current title of the ANSI standard is “TIA-422 Electrical Characteristics of Balanced Voltage Differential

Interface Circuits” and is now in revision B, published in May 1994, and was reaffirmed by the

Telecommunications Industry Association in 2005.

Several key advantages offered by this standard include a differential receiver, a differential driver, and with

correct load balancing, data rates as high as 10 mega baud at 12 meters (40 ft). Several key disadvantages

with the Pason implementation of the RS-422 interface is, high cost of the physical cabling, the absence of any

electrical isolation between nodes and the central communications point, inducted noise accumulated from

parallel high voltage power lines, and the physical damage to the cabling caused by heavy equipment and

common rig ground traffic.

EIA-422 (RS-422) only specifies the electrical signaling characteristics of a single balanced signal. Protocols

and pin assignments are defined in other specifications. The mechanical connections for this interface are

specified by EIA-530 (DB-25 connector) or EIA-449 (DC-37 connector), however common minimal devices

exist which have 4 screw-posts to implement the transmit and receive pair only.

When used in relation to communications wiring, RS-422 wiring refers to cable made of 2 sets of twisted pair,

often with each pair being shielded, and a ground wire. While a double pair cable such as common telephone

cabling may be practical for many RS-422 applications, the RS-422 specification only defines one signal path

and does not assign any function to it.

The Pason RS-422 interface for external devices uses a 10 pin round military connector with 4 pins and 4

conductors called out and a common ground pin between the proximal and distal connections. Electrical

isolation is not present at the proximal end but is expected to have minimal over, under and electrical spike

protection only and is not hardened to current proposed lightning electrical models. This probably is the

reason behind the high number of electrical interface failures and dead ports after lightning strike scenarios.