Fluke Biomedical 956A-201-M2 - Manual (Page 11)

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1.7 UNIVERSAL DIGITAL RATEMETER, MODEL 956A-201-M2
The Victoreen Model 956A-201-M2 is a modified version of the Model 956A-201 Universal Digital
Ratemeter (UDR), when connected to a Victoreen Model 897A-2XY Geiger-Mueller (G-M) tube detector,
comprises a monitoring system that operates over a five-decade range. The UDR provides display,
control, and annunciation functions for the monitoring system, and will display readings in the range of
0.01 to 10
5 mR/h. Refer to Figure 1-2 for view of the 956A-201-M2 front panel.
Standard features for the instrument consist of a three-digit display of the radiation value, in units of
mR/h, R/h, or kR/h, and a multi-colored bargraph indicator that covers the entire range of the UDR. The
bargraph will change color in the event of an alarm condition (green for normal, amber for warning, and
red for high). Front panel alarm indicators and rear panel relay outputs for alarm annunciation are also
included. Front panel pushbuttons are provided to apply power, display alarm limit setpoints,
acknowledge alarms, and to activate the check source. In addition, the 956A-201-M2 is provided with a
front panel mounted TEST pushbutton, that performs a self-test of the UDR.
Analog outputs of 0 - 10 Vdc (1) and 4 - 20 mA (2) are provided for recording and computer monitoring.
The outputs may also be used to drive a remote meter or a local (i.e. near the detector) indicator.
In addition, the 956A-201-M2 is provided with the P/N 942-100-95-M1 dual analog output option circuit
board that provides a 0-10 mV dc analog output.
The 956A-201-M2 also included an internal wiring modification that applies 120 Vac to the Fail and Alarm
relay contacts. The auxiliary relay, K1, is hard wired to operate in parallel with the Fail relay to supply AC
power to a local alarm. AC power is supplied from rear panel connector P1 to detector connector P2.
Refer to Modification Sheet 956A-201-M2MS for additional information on the modification.
All electronics required to interface with the VICTOREEN 897A Series G-M detector are included within
the 956A-201 UDR. The electronics consist of a high voltage power supply, low voltage DC power supply
and the hardware/software required for UDR operation. The system also includes an overrange indicator
to preclude the possibility of on-scale readings when the radiation field is beyond the range of the
detector.
The following paragraphs describe the available options. A separate manual for each option board is
available with more detailed information. Listed below are the option boards currently available.
1. 942-200-75: ANALOG INPUT OPTION BOARD - (Generally not used for normal operation with the
956A-201 UDR, however, it is used if the UDR is part of a simulator) Contains four (4) separate
channels for analog inputs. A 0 to 10 Vdc input or 4 to 20 mA input can be selected independently for
each channel using the jumpers and switches provided on the board. Possible inputs to the board
include: temperature, pressure, flow, or simulated radiation.
2. 942-200-80: COMMUNICATIONS LOOP OPTION BOARD - Designed to enable a EIA RS232C
standard communications link between VICTOREEN's ratemeter and a user computer system or CRT
terminal, with baud rates ranging from 50 to 19200 baud. An asynchronous communication interface
adapter is utilized to format the data and control the interface.
The VICTOREEN Communication Loop Option Board also provides an isolated multi-drop, serial
communications port for interface with a supervisory computer system. The serial data is in a
modified RS-232 format, and utilizes Victoreen's proprietary VICO loop protocol. For maximum
external noise protection, a six-conductor communications cable is used.