Information Systems:Workabout Pro G2 7527C

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Overview

This article is a technical discussion of the Psion WORKABOUT PRO G2 7527C - the model of RF gun used in the warehouse. It is intended as an in-depth, technical reference specific to their use in this company. Refer to the category page for additional articles related to the general topic of RF guns.

Topics

Zebra has a very good knowledgebase. Perusing the site, you can find loads of technical resources including reference guides and best practice documents for the Workabout series of devices, as well as Zebra software (e.g. TekTerm).

Hardware specs

 Note: There are 37 RF guns in total, with an additional 1 unit not in use (fitted with a long-range laser which is not really applicable for our use(s)). The 37 guns were purchased in two batches. Where there are spec variations listed below, it is theorized that the 2nd batch came with newer specs, either because Zebra silently upgraded the model with better/different parts, or because of stock availability at the time of purchase. Regardless of the reason, there are considerable differences in specs between the two configurations, and these differences are discussed in the sections below.
  • CPU: PXA270 520MHz / PXA270M 624MHz
  • RAM/Flash: 128MB / 256MB
  • Wireless radio: Summit Data 802.11b/g CF (Compact Flash) wireless card.
  • Scan engine: Symbol 955 / Symbol 1223HP
  • Other notables: High-capacity 4400mAh battery (as opposed to regular battery), with corresponding battery doors (they protrude more).

Scanning module differences

As previously mentioned, there are two different scanning modules (i.e. scan engines) that can be found in our RF guns - the Symbol 955 or the 1223HP. The physical difference (i.e. just by looking at the outer casing) is imperceptible to the untrained eye, but the difference lies in the laser produced by the module - the 955 produces a solid laster, while the 1223HP produces a flickering laser. This correlates to a performance difference - the solid laser samples at a higher rate, so barcode capture is faster. While users may not know the technical aspect of this difference, they invariably prefer guns with the 955 because to them, they work better (and they have a point). Interestingly, TRG noted a difference in durability between the two units. 

Andy, TRG
The reason you see 'flickering' is like you say, the 1223 oscillates at a lower rate. This is simply because the size of the mirror won't allow it to oscillate at the same speed as the much smaller mirror in the 955. The 1223 has shown to be more rugged than the 955.

This might actually explain why guns with the 955 are more prone to breakage. Technically, they do get more use, so it may be understandable why we observe a higher rate of repair for those units, but users also report odd and temporary problems that could be related to the inherent durability (or lack thereof), of the 955 (e.g. scanner randomly stops functioning and unit needs to be restarted, or device reboots randomly during use after a scan).

Summit Wireless Radio

The wireless card is 802.11b/g, hence it is only capable of connecting on the 2.4GHz spectrum. Legacy (green-screen) applications do not require much bandwidth, so the 54Mbps theoretical max of 802.11b/g is not an issue. Also, the new wireless infrastructure was set to WPA2-PSK authentication, so the new and improved roaming mechanisms found in newer wireless chips may not be an advantage. Other technologies (perhaps antenna diversity and beamforming capabilities) found in 802.11n and 802.11ac may provide minor benefits, but not enough to fully acknowledge the currently wireless radio as a limiting factor for current RF gun usage.

When asked if the wireless card could be upgraded (perhaps to 802.11n or 802.11a (5GHz)), TRG said: 

Andy, TRG
The Summit Client is embedded in the OS load. The OS has to be upgraded to a newer revision to upgrade the client. I believe the latest OS load for the WAP2/3 has client version 3.3. There is no a/n radio option for the WAP2 or 3, only the WAP4; it has an a/b/g/n radio built onto the main board.

Summit Client Utility (SCU)

Despite being an older wireless chipset, the software client actually packs many features found in enterprise wireless. For example, inter-access-point (inter-AP) roaming can be influenced with settings like roam signal trigger, roaming period, and roam signal delta. This software is used to manage wireless in place of the built-in wireless tool in Windows, and the result is a much better and smarter wireless client, which is significant considering the otherwise regular wireless-G hardware being used.

System storage

These units are not like typical laptops or desktop computers where you expect all your data to persist after shutdowns and reboots. A significant part of the OS actually is restored to default depending on the kind of power-on/restart performed. There are three main storage areas that differ in volatility:

  • Flash (reserved) -
  • Flash (user) - Installed applications
  • Registry - stored in RAM, persists across cold and warm resets.

What this means is that depending on the type of bootup/restart, a portion of the previous state is actually wiped and needs to be re-installed. For example, when a device is cold-booted, TekTerm needs to be re-installed.

Persistence mechanisms

Persistence mechanism here really refers to a way to re-establish everything on the device rather than a way to prevent everything from being deleted upon a reboot (as that is just how these guns work). In other words, nothing actually persists, but there ways to make it seem otherwise by restoring everything "as it was".

Generally, there are two strategies for persisting settings/state for the RF guns - through a local mechanism, or through a server-pushed profile. These are represented by Total Recall and MobiControl, respectively.

Total Recall

Total Recall is a built-in mechanism which stores settings into a profile, which in turn resides within the always-persistent registry. Upon booting, the system will look for a Total Recall profile to apply. This is an effective strategy but comes with the following limitations:

  • Total Recall profiles must be set and saved manually on the device itself. The gun must first be configured as desired (i.e. go through and set all the settings in Control Panel etc.). Total Recall can then be used to take a 'snapshot' of the device.
  • No central management - Total Recall profiles can be copied from device to device using a USB, but any change would require taking another snapshot and re-copying this file to all the other devices.
  • Requires similar OS environments. The Total Recall application is baked into the OS and requires

SOTI MobiControl

MobiControl is a far more superior means of persisting settings, and as an MDM software, it provides additional value to mobile device administration. MobiControl is discussed in-depth in this article.

Batteries

As per the Zebra knowledgebase, batteries are rated for 1 year or 300 cycles, whichever comes first. We probably want to stretch this out to 1.5-2 years, since the batteries are maintained fairly well (i.e. they're used regularly and charged frequently).

Operating System

The guns run a specific version of Windows CE 5.0 made for the 7527C. Microsoft is discontinuing support of Windows CE 5.0 in 2020, but this should have little bearing considering that:

a) We do not / did not do any custom development with the OS.
b) It is a Psion-specific version of the OS anyway, so it is technically supported by Zebra.
c) Our use of the gun involves running a single application (TekTerm) and . With the exception of MobiControl continuing support for the CE platform, there appears to be no threat from the OS being branded EOL by Microsoft.

Images of the OS can be downloaded from Zebra's site, but it appears that development has ceased, as the current version (E024p) that is installed on all the guns is from 2014.

Barcode-scanning settings

Another customized portion of the OS is the barcode scanning software (Psion software). The administration can be found in the Scanners app in the Control Panel.

Button-mapping utility

The hardware buttons can be re-mapped.

  • The left button (left scan-trigger) is mapped to the macro Ctrl + c, c, c, which when issued as a key sequence in TekTerm correlates to a sys-request call. This can resolve the Lock-H issue, assuming that it isn't caused by an actual connectivity problem (which most of the time, it is).
  • The right button (right scan-trigger) is mapped to the TekTerm Calculator app.

Physical accessories

Accessories for this gun include:

  • Screen protector - Stopped using them, meh.
  • Stylus pen (not used) - Not necessary.
  • Rubber boot - Critical in ruggedizing the device. Use of the guns without them is discouraged.
  • Battery door - These are actually critical to device operation, as there is a rubber foot in the door cover that when installed presses down on a spring-switch on the device, signaling that the door is locked and allowing the device to power on. The doors are secured using two twist-locks, but these metal locks regularly fall out of their socket. Poor-fitting doors and doors secured with only one lock can cause the spring to disengage during use, thus powering off the device.
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